1994 Sierra transmission not shifting

Hello. I have a 94 Sierra 1/2 ton with 4l60e trans. It sat for about a year and when i went to drive it, the trans would not shift. In OD it has first gear and will not shift. Selecting manually, it will start in first, manual shift to second but when put in D, it will idle down like neutral. If given gas while in D, it drives like in first, however there are no downshift revs on the motor. If I take the trans fuse out, I have second and third manually but no first or fourth. The fluid levels are fine, the wiring seems intact, and the trans is strong. No noise, smooth shifting, and pulled a Jeep over 500 miles with the fuse pulled (really stupid of me I know, but it had to get done). Any help will be appreciated. Thanks, Jacob.
P.S. I've searched countless threads and couldn't find one that totally matched my problems.