My speedometer stopped working and I cannot accelerate. Rpm & odometer are fine. on 2003 Buick Rendezvous

Feels like I can't go faster than 20mph.

Asked by for the 2003 Buick Rendezvous
Have it scan tested, sounds like the transmission is not shifting due to inop. speedometer. Needs to be looked at right away!
A friend of mine replaced my speed sensor and that wasn't the cause. He thinks it might be a cluster sensor but wasn't sure if that could be the culprit for to being able to acceleate.
Did both problems start at the same time?
Yes. I remember because I was at a stop sign.

And i meant that he wasn't sure if it was the culprit for no acceleration.

Update: The problem turned out to be corroded wiring.
1 more answer , 1 more comment
More than likely it's your speed sensor located on your on your passenger side of the transmission. I just changed mine and it's working jus fine. If you jack up the passenger side And take off the tire you will see it.
It seems to be fixed already!