You have two on related problems , just a coincidence they stoped at the same time . The cable inside the cruise control module is probably broken , this cable is connected to the cable that opens the throttle . I'll post a video to show you what i'm talking about !
No Cruise Control Buick LeSabre You can buy this part for $10 to $20 buck ! Change it out in 10 min.
Now your other problem is the Blower motor isn't blowing air out of the vents ? The way you describe it working then on high only an now not at all this could be the motor . Unless the motor was bad enough to take out the blower motor resistor an the high speed relay as well.
Testing would need to be done to find the problem !
Blower Motor Problems Auto Repair Help
If you are willing to test the blower motor and electrical circuit you can find free wiring diagrams here
http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model and engine size . Under system click on HVAC , then under subsystem HVAC controls will pop up . Click the search button ,then the second blue link . Unless your's has automatic ,then it will have blower motor control processor .