Suzuki: Reverse gear has vanished!, shift linkage, suzuki swift

Question
I own a 2000 Suzuki Swift, 5-speed manual. The engine has about 75,000 miles on it. I recently took a long trip with the car and during that trip the right side of the gears began acting up. When gearing up to head home, I tried to put the car into reverse but the gear had vanished. I could only go into 4th and had to push the car. Somehow it magically fixed itself on the way home.
However, now a week later it's acting up again. I tried to use reverse and it just wasn't there at all. 5th gear is also very difficult to get into on the highway during these times.
My only guess has been the cold weather, it's about 30 F at nights. Any help would be greatly appreciated as it's my only car. Thank you so much.

Answer
It could be that some portion of the shift linkage is loose or partially broken, or it could be that ice/snow got in the way.
You need to verify, or have a technician verify that any movement of the shift lever results in a proportional movement of the linkage at the transmission with no unnecessary play.