2.2.1 3g issue -No Service- all of sudden

it just happen out of no where i woke up in the morning and my phone said No Service in iphone 3g 2.2.1
i tried reinstalling yellosnow no luck

does this mean i need ot reunlock ma iphone?

also is there a way to make bkup of my contacts from the winscp a file that i can downlaod that has all my contacts

i have 344 contacts that i don't want to lose nether write them 1by 1 or any app to save them in to my sim card.

oh i tried my sim in other phone works fine