temp. guage on GT6

[Neil Sampson 01276 693030 <neil.sampson@gecm.com>]

Hi there,
just a quick question, as i was cruising back home from a splendid
weekend at the coast in my GT6, the fanbelt broke.  Due to the storage
space in my car i didn't have a spare (along with all the other stuff
you're meant to carry), so the local garage came out & fixed it. 
however, since they fixed it, the temp guage on the dash hasn't moved
from 'cold' - which i know isn't true !  

is it possible that with the heat caused by the fan-belt break the
means of measuring the temperature might have broken ? 

if so, where should i be looking under the bonnet to fix it ? 

(sorry for the very daft and simple questions, but i'm not the best
car mechanic in the world - in fact, not even in my house & i live by
myself !)

thanks in advance
neil 
1973 GT6 - Christine