Sim card wont work read after restart on my phone.

I restarted my phone after using it all day without problems. The phone came back on and stated no service. I checked with phone company and troubleshooted with them. Nothing! I took my sim card out and put it in my older phone worked no problem. Went to the phone store the next day and got a new sim card. Still nothing. Cleaned the reader with air and rubbed a piece of paper in. Nothing. I need help before sending it to LG for repair. I have had this phone for 1 1/2 years with no problem.