Email connection to iPhone 4

[suff]

I have an Apple iPhone 4 which was until recently receiving emails.. However this has now stopped. Apple suggested I contact my service provider (TalkTalk unfortunately) but they haven't responded to my mails (from my PC).
I recently changed my PW for Email access on my PC & have tried changing this (using the same PW) via settings on my iPhone - but no joy.
Anybody help please? Should I try & re-sync my phone again via itunes?
Thanks

[suff]

PLEASE CAN ANYONE HELP WITH THIS IPHONE PROBLEM??