1999 Toyota Camry Car RPM's Revving high on freeway

let's start with checking the codes.
https://www.2carpros.com/dia/how_to_scan_trouble_codes.htm

Checking the codes doesn't really do me any good seeing that I'm not a mechanic. I just wanted to know what the symptoms sounded like it could be.

there could be a problem with the engine, and the computer switched into "limp home" mode.
which normally puts the transmission in 2nd gear and keeps it there.

there could be a simple problem with the transmission like a speed sensor that has failed and the computer doesn't know what gear to put the transmission in.

there could be a major problem with the transmission.

the codes would give us more information to help prepare you for what the problems could be.

I do not know about the check engine light problem but I have a 99 Camry. Overdrive should always be ON (engaged) not off. You only put it on the OFF position when you are towing or on a steep mountain roads. If overdrive switch is OFF, that is normal, 4000 to 5000 RPM on the freeway at 65 to 75 miles per hour. If overdrive is ON, RPM should be 2750 to 3000 at 65 to 75 miles per hour.

Took the Camry in and got it checked out, the speed sensor in the trannny was faulty, according to the codes.
Thanks for the help.

that's great

sounds like it will be the cheapest and easiest fix out of the many possibilities.