my westie jessie is 17 weeks and is currently growing her adult teeth as far as we can tell. she wont let us near her mouth, is'nt eating, barely drinking and sleeping nearly all day. is this normal behaviour? she also sounds very nasally like shes congested but her nose is not running. little worried as out of character for her. anyone got any advice or reassurance.

Sounds like a trip to the vets is needed, the nasally/congested sound isn't normal.
Please let us know how you get on at the vets with her. Best of luck.

Yip off to the vet I would suggest.   At 17 weeks the teeth generally are still at the falling out stage I would expect eating to be pretty normal.  I have a 15 week old no teeth lose yet. 

When you say she is growing teeth what is she does in particular that makes you think this?

i'd be off to the vets straight away, this doesn't seem normal at all. i've never had a dog not eat because of it's teeth and with the other things you've mentioned i'd think there's a problem else where.
let us know how you get on.