Computer not recognizing my CD ROM

my mom has been scammed by a rip off computer repair person in Chandler, AZ and I am going to attempt to get the dell that he said was shot to work again. it started when she bought the garmin gps and Best Buy had her buy the 20$ disk and my son and I could not get it to download so instead of my Mom just trying the GPS she calls some stranger to look at the computer, anyway the GPS had the info already I guess and thats why it would not download. This guy sold my Mom a HP and she put the Dell under her desk for 2 years, She does a refrag on the HP and it messes up so she CALLS HIM AGAIN and takes the HP home calls her to say it also is shot and she tells him to keep it with all her info on it, she is not too bright sorry to say. I took the Dell home and its working decent but CD ROM not working I opened the back and it has 2 CD ROMS but the computer not recognizing them can someone walk me through the connection process?