Transmission not shifting

So, I have a 4L60E in my vehicle. Just the other day I was given the truck and it was RPMs, it was finally shifted and that would be the only time it shifted. I would ride around 3,000 RPMs at 60 MPH.
There was a code reading for Shift solenoid 1-2. Which I replaced, along with the transmission filter, gasket and even threw 6 brand new NGK spark plugs in.
I also just did a brand-new exhaust manifold, exhaust manifold gasket, O ring and O2 Sensor replacement due to an exhaust leak.

Since doing all of these repairs and replacing all fluids, the truck doesn’t want to shift whatsoever. It will go into drive and will accelerate, kind of sluggish but will not shift.
Please help! I have work in the morning, and I just started this job. Now I fear I won’t make it. :(