Restore IMEI for Samsung Galaxy SL (GT-I9003) when there is no backup Well I was on phone and suddenly I lost IMEI and my SIM card is not detected.
So I tried flashing (to some firmware and I flashed back to original I9003XWKPG) and nothing.

I don't have any backups. I have Samsung Galaxy SL (GT-I9003).

How can I restore my IMEI? 

(Click image to enlarge)
Were you messing around with poweruser settings because most of us don't suddenly "lose IMEI"  but in that case if you are rooted get an app called root explorer and go to the following directory /system/efs and see if your imei is in there. otherwise you will have to buy a new phone.