This may be Roy Butfoy's province; generally, if the car won't engage reverse, either you have $ERIOU$ transaxle problems, or more likely, the shift linkage is at fault. Drain the transaxle oil and look for metal debris in the drainings. Refill with 'almost' a gallon of 75W90 posi-type gear oil. If no chips or bolt-heads are found, get out your Owner's Manual and carefully go thru the steps for centering the shift lever in the cabin. Depending on where you are in the country, there may be other owners nearby that are more familiar with the car and could point out the problem area with your linkage. Without seeing the car, thats about all I can recommend.