Hi Paul,
I've merged your pleas for help together in one posting as a bit of a forum tidy up so hope you don't mind.
I don't own this type of radio so unsure of what has happened but there is always the old fall back of - have you tried to reset it?
Page 23 of the manual linked below gives details of the 'reset' procedure :-
http://www.radiomanual.info/schemi/Vari/Quansheng_TG-UV2_user.pdf
(Actual printed page of '23' but may be 27 on a pdf viewer.
)
I know that would be a pain in that you'd have to program the radio all over again but I suppose that's better than having a radio stuck on one frequency.
Maybe worth a try?
Let us know how you get on.
(Otherwise it's a perfect excuse to purchase one of the newer 'hackable' Quanshengs everyone's raving about.)
All the best,
Victor