N95. i bought my n95 2nd hand from a mobile fone shop i got 2wks warrenty with it , had no

Question

i bought my n95 2nd hand from a mobile fone shop i got 2wks warrenty with it , had no problems until 2 days ago after charging it up for a few hrs i turned it on that was ok but i went to dial a number and the number 2 button came up on screen as 7283# and no matter which way i try it the 2 button seems to be no longer a2 , it seems to be doing as it wants the music player just comes on as and when it feels like it can any one plz advice me on the best solution would re formatting the fone solve the problem