Transmission issues.
 

I've taken care of my 98' Camry for as long as I had it, which has only been about a year. Two weeks ago, my transmission started failing on me. I would have the car at 3000 rpms just to get up and go. Later that day, it got worse and worse. 4000 rpms, then 5000, and then nothing. It just wouldn't go. I can however go in reverse. It's really strange. I've done my share of research and found out that it could be many things. I bought the car from my mom, and she told me that she doesn't remember the last time she changed the trans fluid. I really don't want to lose the car. My friends and family have had so many memories in it. Everyone loves it. Right now it's sitting on a sidewalk in front of a friend's house risking getting towed. What do you guys think it could be? I'm seriously down to fix it myself, I just need to know what, so I can get whatever I need before I begin.

Might review posts at this site and Toyotanation.com as your situation has come up before.

Determine if the trans fluid level is OK and that the gear selector lever on the trans that connects to the shifter inside the car is moving in sync with each other (no shifter cable problems).

Could the one-way clutch in the torque converter is bad.

Or bad clutch or brake inside the transmission.

Or problem with shifter body inside the trans. This body has various valves, etc and is what directs the trans fluid under pressure to the appropriate trans components for them to operate.

These last item can be accessed by removing the trans oil pan. The other two trans items requires taking the trans out of the car and perhaps taking it apart.

I also received a code for a shifter solenoid. Does that isolate the problem to something more specific? Or could it still be any of those?
Also, the fluid did seem to be leaking a little, but it was hardly noticeable. I refilled it, but with Lucas. I'm not too sure if it was a good idea, but it didn't work..

What was the code?

Yes, certain codes can be linked to these symptoms. Unfortunately the causes of the problem (and code) could still be issues stated previously.