I just received a work permit and I have Type O visa. It is a single entry and I have yet to extended it for a year. I have been invited to laos for a wedding..I will go next week and because of this I will lose this single entry visa...If I came back in the country by plane with a 30 day stamp, I obviously no longer have my type of Visa, but I still have a work permit, but without the proper visa, does this render the work permit invalid?

yes

You should get a single re-entry permit (1000 baht) to keep your 90 day entry valid. Then do the extension.

If leaving from either airport in Bangkok you can get a re-entry permit 24 hours a day.

Get a re-entry permit from immigrations for 1000 baht, that way your non-O will not be void.