I have an unlocked iphone 4 but my computer doesn't detect my iphone 4 anymore.

Unlock your apple iphone 4 and use any other carriers sim card
To unlock your apple iphone to use any sim card, you need to get the unlocked confirmation from apple by using any unlock code service provider.After getting the unlock confirmation you need to use i-tune to unlock it
here is the direct link of service provider to get the unlocked confirmation
How to unlock iPhone Factory Unlock iPhone

After getting the unlock confirmation you need to use i-tune to unlock it as below:-
How to Unlock the Apple iPhone 6 after getting the confirmation as Unlocked -

-Install the last version of iTunes on your computer.
-Make sure your iPhone 6 is updated with the lastest version of iOS.
-Switch ON your iPhone 6 with a SIM Card from a non-compatible network.
-Connect your iPhone 6 to your computer using the Original USB Cable.
-Launch iTunes andwait until iTunes detect your iPhone 6.
-Now disconnect your iPhone 6sand reconnect it after 10 seconds.
-Your iPhone 6 is now Unlocked!

Note:-In the unlikely event that your iPhone 6s is not unlocked, please restore your device following the official guideline from Apple - https://support.apple.com/en-us/HT201252

Hi, You can unlock an iPhone 4S locked to Telus network using remote unlocking service. This method of unlocking is safe, simple,. affordable and quick. you can get the remote unlocking for an iPhone 4S from www.prounlocking.com/apple-iphone-4s/rs16wp9/ at affordable cost with easy instructions on unlocking. This method of unlocking also doesn't require a Jailbreak too.
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UNLOCKING STEPS FOR AN iPhone 4S
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1. Wait for us to send you an email saying your phone has been activated or remotely unlocked.
2. Install the latest version of iTunes.
3. Make sure your Apple iPhone 4S phone software is updated to the latest version using the iTunes software.
4. Connect your Apple iPhone 4S to iTunes with a NOT ACCEPTED SIM card.
5. Wait until iTunes detects your Apple iPhone 4S.
6. Disconnect your Apple iPhone 4S and reconnect it after 10 seconds.
7. Your Apple iPhone 4S is now unlocked.

Look here: unlock iphone service

Sure you can, but before you must unlock it
http://jailbreak4iphone.com
This will help you to unlock any kind of iPhone.

If you have problem in accessing with any specific SIM card in your iPhone, You can make a complaint to your network provider and get a new one.
If you are not able to access any SIM card in your iPhone, Take your iPhone to a local mobile store.
If you are not able to access any SIM card other than a specific SIM card in your iPhone, then your iPhone must be network restricted. You need to unlock it.
The safest and easiest way to unlock an iPhone is to unlock through remote unlocking method. You can get the remote unlocking for an iPhone from www.wickedunlock.com/apple/rs11wp8/ at affordable cost. This method of unlocking doesn't require a Jailbreaking too.
Here are the steps to unlock an iPhone,
1. Wait for us to send you an email saying your phone has been activated or remotely unlocked.
2. Install the latest version of iTunes.
3. Make sure your Apple iPhone phone software is updated to the latest version using the iTunes software.
4. Connect your Apple iPhone to iTunes with a NOT ACCEPTED SIM card.
5. Wait until iTunes detects your Apple iPhone.
6. Disconnect your Apple iPhone and reconnect it after 10 seconds.
7. Your Apple iPhone is now unlocked.

You can get the Remote Unlock service from the site
www.unlock-zone.com/supported-phones/rs5wp7/ and unlock it easily.

Hi, You can unlock your iPhone4 safer and easier through remote unlocking method. It is also an affordable method too. You can get the remote unlocking for your iPhone4 from www.wickedunlock.com/apple-iphone-4/rs11wp9/ Here are the steps for unlocking an iPhone 4,
1. Wait for us to send you an email saying your phone has been activated or remotely unlocked.
2. Install the latest version of iTunes.
3. Make sure your Apple iPhone 4 phone software is updated to the latest version using the iTunes software.
4. Connect your Apple iPhone 4 to iTunes with a NOT ACCEPTED SIM card.
5. Wait until iTunes detects your Apple iPhone 4.
6. Disconnect your Apple iPhone 4 and reconnect it after 10 seconds.
7. Your Apple iPhone 4 is now unlocked.

You can unlock the iPhone4 through remote unlocking method. This is the safest and affordable method to unlock an iPhone. You can get the remote unlocking from www.Wickedunlock.com this site provides accurate unlocking solutions at low cost. you will be guided with step by step information on unlocking process.
Here are the steps for unlocking an iPhone4,
1. Wait for to send you an email saying your phone has been activated or remotely unlocked.
2. Install the latest version of iTunes.
3. Make sure your Apple iPhone 4 phone software is updated to the latest version using the iTunes software.
4. Connect your Apple iPhone 4 to iTunes with a NOT ACCEPTED SIM card.
5. Wait until iTunes detects your Apple iPhone 4.
6. Disconnect your Apple iPhone 4 and reconnect it after 10 seconds.
7. Your Apple iPhone 4 is now unlocked.

When it comes to unlocking Iphones, Remote unlocking is the best method to be followed or used. . you can unlock your phone instantly within few minutes. This site Unlocking4U.com offers remote unlock for the iPhone. here are the instructions to follow while unlocking the iphone.

1. Allow us to send you an email saying that your phone has been activated or unlocked remotely.

2. Install the latest version of iTunes.

3. Make sure your iPhone 4 phone software is updated to the latest version using the iTunes software.

4. Connect your iPhone 4 Apple iTunes with a SIM card not accepted.

5. Wait until iTunes detects the iPhone 4.

6. 4 Disconnect the iPhone and reconnect after 10 seconds.

7. 4 Apple iPhone is unlocked.

When it comes to unlocking Iphones, Remote unlocking is the best method to be followed or used. . you can unlock your phone instantly within few minutes. This site offers Theunlockarena.com remote unlock for the iPhone. here are the instructions to follow while unlocking the iphone. Do not enter wrong unlock codes into your Apple iPhone 4 mobile phones. If you enter more than a certain number of unlock codes on your Apple iPhone evil 4 mobile phone, the phone may have an ******** locked, and can sometimes be used. 1. Allow us to send you an email saying that your phone has been activated or unlocked remotely. 2. Install the latest version of iTunes. 3. Make sure your iPhone 4 phone software is updated to the latest version using the iTunes software. 4. Connect your iPhone 4 Apple iTunes with a SIM card not accepted. 5. Wait until iTunes detects the iPhone 4. 6. 4 Disconnect the iPhone and reconnect after 10 seconds. 7. 4 Apple iPhone is unlocked.