1990 Ford Mustang Not able to shift into gears

I have a 90 ford mustang, my wife drives it for a daily driver. Within the last couple of weeks she has been complaining that it has become harder to shift. She was saying that she had trouble getting the car in gear. Tonight about a block from the house we were stopped at a stop sign and she put it in first gear we took off and started to go down the road when she went to switch gears it wouldn't come out of first. She had to pull it out like she wasn't even pushing on the clutch. Luckily we were in front of the house. Now when I try to put it in gear it feels like the clutch is not disengaging. The clutch cable and quadrant are less then two years old and the clutch is about 5 but only has about 3 years of driving on it the clutch is a center force Dual friction. I have done a little research and I feel that it may be the fork because for the the last month and a half when the car was in neutral and running their was a little squeak that would go away when in gear. Could you please tell me if this may be right and also what is the labor time on the repair if so.