Clasp on my smeg sc336x oven door has closed and I can't close the foor?

You could always find the manual and look in there. Try Section 10.6

No manual? You could try Smeg themselves - there are probably support pages on their website. Nothing there? There's a really useful thing called Google you can use to search the Internet. I found this within 2 minutes:

http://www.manualslib.com/manual/155520/Smeg-Oven-Ap361mfeb.html?page=21#manual

XXX
November 2015

Look on youTube - there will probably be a little piece that you can flip up to release the hinge and flip down to lock it again

Pay more attention
November 2015