I have travelled to the US on B1/B2 visa and later on an F-1 visa. Due to a personal emergency I had to leave midway in the program while I was on an F-1 visa. But I'd informed the graduate office, my professor and completed the necessary formalities.
Will I face an issue if I were to travel to the US again. Do I need to reapply for a US visa since I already have a B1/B2 visa which is still valid?
I didnt have any issues at the port of entry, it was pretty smooth. He just asked my purpose of travel and stamped me.
Unless your B Visa or F Visa have been revoked and stamped as such as documented here you should still be able to enter US if one or the other Visa is still valid.
One thing that I can't find yet is whether or not obtaining of F visa supersedes B visa but I don't think it should.
EDIT
On the subject of F visa superseding and invalidating the B visa you can obtain this information at the local consulate.
If you enter on a B1/B2 visa they can only give you a duration of stay of 6 months or less. To resume F1 status and be able to stay as long as your program lasts, you need to enter on an F1 visa.
