I am on OPT now (F1 expired 20/17/08). Can I renew F1 in canada?. Can I come back to US if my F1 denied?

Question

Now I am working for a company in US. My OPT started on June 1st. I want to travel abroad and come back to US.

Answer 1

8 CFR 214.2(f)(13) Temporary absence from the United States of F-1 student granted employment authorization.

(ii) An F-1 student who has an unexpired EAD issued for post-completion practical training and who is otherwise admissible may return to the United States to resume employment after a period of temporary absence. The EAD must be used in combination with an I-20 ID endorsed for reentry by the DSO within the last six months.

Naturally, the normal passport and visa requirements would apply. In your case, you would need to have a new F-1 visa. If your visa application was denied, that would leave you without a valid visa with which to return.

"Renewing" your visa in Canada would be unlikely unless you have some sort of resident status in Canada. Also, Immigration  Canada isn't going to be anxious to admit you.

They would fear that you might be denied an F-1 visa at your interview.

Answer 2

You can only apply for a student visa from your home country.  If you go traveling, you have to go home.  There you can apply for another student visa (it expired, it is not "renewable") if you have not yet completed your course of study.  But how did you get OPT before you finished your coursework/degree?  Another F1 visa does not appear possible, unless you took practical training before you finished up the degree requirements.

Student visas are issued on the condition that you return to your home country.  If your F1 is denied, you cannot return to the US, even as a tourist, for at least two years.