If you used a script to install it, the script requires you to specify a JRE version. If that version does not match the version installed, it acts this way.
If you use Jeremy Davis' easy solr script, you have to specify the version as a variable
$JREVersion = "1.8.0_201"
If you look on your hard drive, in program files look for the JRE version. Make sure it matched the version it was when you ran it.
C:\Program Files\Java\jre1.8.0_201
If it does not match, the edit the JAVA_HOME path in your windows environmental variables. Then start SOLR again.
