mobile phone please help a novice?

[itsybitsy1-2-3]

please help,
i just bought my first mobile phone, a virgin lobster, i opened the back to jot down the registration no. as it recommended, didn't touch anything, put the back back on now it won't work!
i tried pressing all the buttons (one in turn) but nothing!?
it must still be working as it lights up and plays a tune when i put it on the wall charger.
please tell me what i done or didn't do to stop it working.? it was great before i took the back off.
thanks in anticipation
betty

hi all, I took it back to the shop, mr. magic finger fixed it! (can't work it out, i pressed the same button that he did) ha ha

bet

[vikeor]

check if the battery isnt loose...