Hello @elmaazon,
if you deactivate the plugin, it is normal to have not working long permalinks.
The plugin gives you the ability to have long permanlinks (much more characters in your URLs compared to what WordPress allows by default). If you remove the plugin all your long permalinks will not work, since the required functionality is not in place any more.
All URLs that are not long should be working fine. You can try this actually. Create a post with a small slug of only some latin characters for example, this must be working. The same is true for old short URLs.
In order to have your links working without the plugin you must have much sorter URLs. For example after disabling the plugin, edit one post and regenerate it’s slug. It will become much smaller and will work. You can also use some solution to make all your slugs sort at once (I am sure you can find many plugins that will generate slugs again, in order to have the sort ones).
Thank you.