Unhappy Help! Lg Optimus Net P690 NO SERVICE

Hello,this is my first thread here.I have big problem with my LG Optimus Net p690.Today I rooted the phone and then install CyanogenMod 7.2. When I wanted to set my minimum CPU frequency to 250MHz the phone rebooted and since then l ran out of service. I reinstalled the original software but nothing. Can you help me? please