upgrade of draftsight 2016-2017 has made draftsight professional unusable

Hi,

the computer asked a question to upgrade draftsight from 2016 to 2017 and it was accepted.

This has now made draftsight unusable. It is just freezing.

if  a 2016 draftsight license was purchased, does it work with 2017?

If if not, how do I install 2016 back on the machine as it can't be found on the machine.

 

thanks

Kim