I heard that there are two solenoids. When I check underneath, the only sensors I can find are the speed sensor and the neutral safety switch. The problem that I am having started last Wednesday. The night before we had some pretty good snow and my blazer had no troubles traveling anywhere. I made it home like usual and the next morning when I was taking my wife to work, it was very sluggish (under 25 mph) for about 200 yards before it sat it wouldn't go any further. And now it don't go forward or reverse no matter what gear. After it sits for awhile (1 day) it can go forward for about 5 yards and then sit still. It has fresh fluid and filter

 

Is there any pictures or layouts for them

 

There are a few different electrical items inside the transmission pan. It is possible that during the fluid/filter change any one of these items and/or the electrical harness that connects/controls them were damaged.

For an illustration of the transmission control solenoids, etc, check out any one of the transmission related DTC posts from the OBDII Code Index link listed in my signature (example - P0751 Explained).

One other thought on your problem. It may be possible for the filter to fall out of the retainer in the transmission case if it was not properly seated during the service. This would cause a lack of fluid pressure to the transmission which would result in no movement.