I'm trying right now to repair the reactor and I have the necessary part(s) but when I enter the reactor room it's nearly empty and there's nothing but construction signs and things of that nature, as well as a hole in the middle. What do I do from here xl?

Wrong reactor, that's the broken one. On the first map there is a large building to the east, open the door and go inside.

Thank you ! I feel a tad unintelligent now but ah well, also while I'm here could anyone tell me how to recruit Lenny ? He seems to have to same dialogue as before I fixed the reactor which means I can't recruit him.

Sounds like you may be at your companion limit. Your limit is half your charisma.

I don't have any party members and haven't for this playthrough yet, I just started.

You have to talk to him about the past, and how he once saw the Vault Dweller.