How do I reinstall turbotax? My original installation was corrupted. When I try to reinstall software turbotax tells me that license has already been used.

How did you install the program the first time ?   And how are you trying to do so now ?

From a CD   or   from  a download ? 

For WIN  or  MAC ?

downloaded  program on Mac. have cd. don't have a drive

For less then $20 you can get a CD reader which you may need for other things.  Or if you have the installation file on the old computer you can download it to a thumb drive to transfer to the new computer. 

But if you used the CD for the original installation and now need to download the program ...  

https://ttlc.intuit.com/community/installing/help/i-bought-the-cd-but-my-computer-doesn-t-have-a-cd-...

Cd purchased.