I took the bladeoff to oil and now can't remember how to get it back together.

well...IMO though getting things apart is easy but getting it back together might be a pain if you dont remember the steps you took to remove it

try utube for a video on putting together or try Electroilux website for the manual.

One shouldn't take things apart if one cannot re-assemble them :D
Take it to your local vac shop.

If there is a leak in the head gasket it will never run properly. Maybe the carburetor is plugged if it has sat for a while. The gas/oil mixture can go bad over time. The leak could be from a loose gas line. Or possibly even oil dripping from the oil filter if you just cleaned and re-oiled it.

Check your owners' manual or call the manufacturer.

you can download a manual from here
http://safemanuals.com/user-guide-instructions-owner-manual/ELNA/2110-_E

take the back cap off of the nailer. There is another loose cap in that head, most times that gets stuck. Believe me, I was raised by a carpenter that had nail guns before anybody else did. Also, sometimes that plunger gets bent, just straighten it out. Check for blown o rings. If it is old, take the trigger assembly out and clean it out. Be sure to oil everything well before you put together. We use marvel mystery oil, or nail gun oil.

took cover off to wash and can not remember how to put it back together

remember the last thing you took off and start there,work your way in reverse towards the first thing you took off

Here is a breakdown of the parts in diagram form:

Whirlpool Model #ED25QFXHW02

Hope this helps, please remember to review!