Karen I would think it is time for a reset and see if it makes a difference. This is what I found how to reset you phone
"Code to reset the Nokia 6760 slide mobile
1.- Basic Reset or Soft Reset for nokia 6760 slide
This option restores the .ini files from the ROM.
Does not erase data (photos, videos, documents) or applications from
a third party. Key Code *# 7780 # (click this combination of keys on the
keyboard in the mobile)
2.- Total Reset or Hard Reset for nokia 6760 slide
This option restores the original operating system from the ROM.
Formats the C: '''partition and deletes all data including the memory
card. '''Key Code *#7370# (click this combination of keys on the keyboard
in the mobile)
or
Turn the device off.
Press and Hold “*“+ “3” + Call / Green Keys.
Turn on the device by pressing the on button.
Wait until the Nokia logo appear.
Important: To proceed to reset, the battery must be full and the
mobile device connected to the charger. If during the course of reset,
the mobile stop receiving electricity it can ruin the internal flash
memory of the mobile device and stop function." [http://www.resetnokia.com/nokia-6760-slide-reset-code/|from here]
Most importantly make sure that you understand that '''YOU WILL LOSE YOUR DATA '''with some of this. I guess at this time you do not have anything to lose Good Luck and let us know how it is going. BTW, the security code is 12345 unless you changed it previously .