There are two things I would check:

First, was the rear wheel put back in the same position in the dropouts? If not, it could cause interference between the rear derailleur and the cassette, and prevent you from shifting to your easier gears. To fix it, change the position of the wheel or the b-tension screw adjustment on the derailleur.

Second, the cable housing that runs from the shifter to the derailleur may have gotten bent, pinched, or otherwise damaged while you were taking the heel in and out. That could prevent the inner cable from being able to move and change gears. If this is the case, you could try bending the cable housing back, or you could replace it again.

Since you mentioned that shifting does not work up or down, I would lean towards the second possibility. The first issue would only prevent you from shifting to your easiest gears.