3 speed transmission issues

[Swatson]

I can shift between 1,2, and 3 but the shifter wont go into reverse. I can get under the truck and physically put it in reverse and then it will work, but then it won't let me shift out of reverse to anything else until I climb under it and move it out again. I had a guy doing some work under the truck, and before It all worked fine. I'm not sure if the linkage parts are hooked up correctly. Anyone have any advice? The linkages are on the side of the transmission.