How to re-connect the brain or computer, its set to manual..? need to un-set it

[NaturalAspired]

I just got this car the people who gave it to me said it needed a alternator, so I put one in there. well its not working..on the alternator I notced a sticker saying "This unit is externally regulated by the computer" and now the old owners are telling me that the "brain" is un-plugged and the computer is turned to "manual". I checked the "check engine light" codes and it says the generator isn't working and the computer has been unplugged. I looked at the comp and it looks plugged in (that is the computer under the hood all the way to the right, directly underneath the add washer fluid tube?). Does anyone know what the heck I'm talking about? I really really appreciate any help or advice!!! Thanks in advance

Dave

[skatendestroy]

yes that is the computer it a silver box (depending on what year) well therea whole mess of wwire thats connect to it in the back there is a bolt that acctually connects the connector to the ecu check to see if its tightened or not if it isnt the two connectors wont touch check that out

but the weird thing is if the car starts and the ecu isnt connected the car shouldnt start at all.... due to the fact that ignition fuel injection is all controlled by it....... so i think it should be connected

[NaturalAspired]

I just found out that the computer was set to manual and/or unplugged. However, this was done 2 years ago and the car has ran since fine...until now. The car sat for about 8 months 'til I got it and thats when the problems arose. I just don't know what to do...maybe I got a bum alternator?