I have 2009 Cadillac SRX, I was accelerating and my transmission stopped working

What is your question?

After a few seconds I was able to continue on for a short distance, then nothing. Left it sitting overnight, then I was able to drive it about a mile, then it stopped working again. After several hours, I was able to move it a little farther to get it to my house. What’re should I start my search to figure out the problem? Car has 157,00 miles on it.