Hi my name is*****'m a 30 year veteran engineer. I think I can help.
Can you look and see if the battery case is loose please?
In that case, please remove the battery from the phone, wait 1 minute and then replace the battery and power up the phone.
Please let me know when this is complete.
Ok, now try to use the phone and see if that fixed the problem.
I'm sorry this is happening, I know it's frustrating. I believe the phone may have absorbed some moisture, and unfortunately, in this case the phone would need to be repaired (most likely not worth it), or replaced.
OMG! That figures right?
Unfortunately it's a pretty basic phone and not rated as the most reliable.
I'm assuming you don't have a contract with the carrier?