When ever i plug in my ac adaptor in laptop , the touchpad freezez,,, withouut ac power it works ok...

check AC - DC adapter could be faulty
Check surge protection if plugged into a surge protected powerboard
Could have a crook powerboard

Sounds like there is a serious fault in the motherboard. I'm assuming you checked that the AC adaptor is working ok? Check first that there is power to the adaptor and power out of the adaptor by ensuring the green led is on and not flashing, a flashing led indicates power is not making a circuit in the motherboard and therefore a faulty powerboard.

Check the light on the AC adaptor when plugged in to the laptop. If it is flashing, it indicates that the power is being "spat back". That is, not completing the circuit. Means that you have a fault in the charging circuit. I'd check for burning around the contacts where the DC port was soldered onto the board / or if the plug type, check the socket on the mobo is not damaged and is firmly soldered on.

After that, (if not already done) check the output voltage of the adaptor with a multimeter, might be a simple failure of the ac adaptor, even though it looks ok

remove the battery, unplug the power adapter. press power button for 30 sec. then connect the power adaptor. press the power button.

if this didnt work you can contact your laptop's manufaturer to run test for your pc..

you can contact this num: 866-539-3901.

Remove the battery and plug the ac adaptor in check wethere the light on the port where you connect the ac adaptor glows or not, if no then check the wethere the ac adaptor is getting warm or not after you plug it in for few minutes if not then ac adaptor has to be replaced.
If the light on the port is glowing then it is likely that the power supply of the notebook has gone bad as it is not able to switch to ac adaptor or the port where you connect the ac adaptor to the notebook has a short circut when the acadaptor pin is connected , better try with a different ac adaptor to be sure wethere the issue is with ac adaptor or the notebook.
My best wishes

If the power point is ok try using another AC adaptor of some of your known person who is using the same laptop, and check it should work else the fault will be with laptop and you need to get the same checked at the service center,
make sure you do not open the laptop on your own as you may loose the warrenty of the same

Let me know if this will help

Regards

Did you wiggle it a bit when plugged in? You can't tell from looking on the outside if the plug is fine because it goes bad inside where it is soldered. This is a very common problem, and have fixed many laptops with the same problem. All of them had a bad solder connection inside. Did you dtermine the plug was fine by plugging another ac adapter to your laptop or you just checked it visually? Hit me up I will solve this one for you.

does your trackpad heat up over time when it is on ac, and try going into your bios and setting the option for performance on ac power and battery power to the maximum

sounds like the power connector (where you plug into pc) is going bad. try twisting / wiggling connector. pause for a few seconds between twists to give circuitry chance to reconize power input. sometimes there is a green led that will light up when power adaptor is inserted. you can use that as a reference.

if the touchpad is working fine with the battery and if it is not working with the ac adaptor then in this case u can try with the different ac adaptor and still if it does the same thing then uninstall and resintall the toouchpad driver and restart the computer and still if it does so with the ac adaptor then u need to open the laptop chasis and then u need to fix up the power supply connector in the motherboard where the power supply from the ac adaptor is not getting the adequate response from motherboard.