Network coverage problem after select 'reset all' mode for my Sony Ericsson W350i cell phone

for sending text messages :
1.go to your message settings and check the message center number to see if it is correct
2. call to your network operator customer care
3. request the message center number...
4.note it down
5. go to message settings>message center number
6. insert the number which is noted by you and save it

this solves your messaging problem ...
Good luck

i think thats no a Software Problem,but that is a hardware Problem.
Try to Rehoot you IC PA (IC Power Ampilifier) or Change it if still no network.
But if you want to try to Upgrade your firmware,
you need using Sony Erricsson Update Service for easy ways.
just download and install Sony Erricsson Update Service,Connect your phone to Computer using data cable,and Sony Erricsson Update Service will found and upgrade your phone firmware automaticly.
you can try download Sony Erricsson Update Service from SonyErricsson Oficial Site.
and you can found The Tutorial for using Sony Erricsson Update service in HERE

Try factory Reset ,after removing SIM and MSd cards.

*#78737322867973738# -> Super Factory Reset

did you hit your phone?
try making 'Master Reset' (settings->master reset).if this doesn't work try flashing phone's firmware

HI,

Go to the Video Size option. There you can find
Original
Auto Fit
Full screen

Select Full screen to view in full screen mode.

how can get net work coverage in k800i sony ericsison mobeile phone

Sounds like your phone is stuck in flight mode for some reason. Have you tried a Master Reset (you will lose all your personal data if you do this). 

Getting cell switch off when lisning 2 music?

Try setting your handset to manual network selection and select the network for your connction provider. If you don't roam around much, this works well. Please revert back to the automatic network selection if you go on Roaming.
Try & reply.