What you have is a broken window regulator. This is very common. If the cables are off, it is because the plastic guides on the window regulator have broken. The only way to fix it is to replace the regulator assembly. It is kind-of a waste, because your motor is probably working. The window regulator will come with a new motor. You can buy a motor without buying the regulator, but you cannot buy the regulator without the motor.
You didn't mention what year and model your Buick is, so I cannot give you any specific information. However, your regulator assembly should look like one of the regulators pictured below. Both of these are available at most aftermarket auto parts outlets.
The entire assembly is pretty easy to change. The hard part is getting the door panel off...you said you have already done that, so it is downhill from there. Everything should be held together with several 10mm head bolts (usually 7 or 8 of them) and one electrical connector.
I hope this information helps you to get your window fixed. Please let me know if you need further assistance.
Thank You for your patronage,
- Dave (dttech)