Guess you're not a regular Nxt user. Still it should be simple. Nxt does not need to be installed. Go to https://nxtforum.org/nrs-releases/
and choose 1.4.18. I have had problems with 1.5.9 as well. Verify the hash with something like onlinemd5.com and extract the folder to your
desktop. Double click run.bat and leave the command window open until blockchain is fully dled. Depending how fast your computer and
connection is it could take a couple hours to half a day. Open a browser and go to http://localhost:7876/. Type your passphrase and there
really should not be any single problem.

I believe the problem with 1.5.9 is you have to update to java 8. Get java 8 then "install" 1.5.9.