Check Engine Light!!!!

i removed the cover for my headers to clean it and when i did that i unplugged the wires for the oxygen sensor(i think that is what it is) and when i installed it back on i forgot to plug it back!!! so then i started my engine then the check engine light turned on and i suddenly remembered the wire!!! so then i turned off the engine and plugged it back in. but the engine light still remains on. my friend said it should go off within 3 more trips but it has been almost a week! would there be any damage or do i just need to have somebody reset it?