Okay, I hope I am not too late and you took your phone in... YOUR ANSWER is simple....
First, is your diag port enabled? Dial ##3424# to enable it if it does not show up on the computer. Plug it in and connect with cdma workshop 2.7 demo. Then go to the security tab and tell it its a LG and read your MSL...
Now go to your dialer and put in ##VIRGIN# click on edit and fix your problem! The MDN is you phone number and the MSID is the other number Virgin Mobile gave you at activation. Don't remember just call and they tell you again. Anyway, finish telling your phone its number and it will reboot and everything is back to norm.
EMERGENCY BACKUP INSTRUCTIONS
If you aint rooted and you cant get port open and msl is still outta reach and everything is conspiring against you... Don't trip I got this too!
Get somewhere that will give your phone internet via wifi or itself. Then go to your browser and get to filecrop. Get LG_OE_DiagMode_Debug apk then Poot-debug apk and last Ministro2 apk. Run them in that order and your port will be opened, you will be rooted and ready to plug into cdma workshop for your MSL.