You should try using 'Clear data' before you do an Uninstall. Using Clear data will remove the app's settings and configuration settings, and the app's cache. Then try to install the app from the Play Store.
Using Clear data does not remove your saved music and video files. It pertains to the app's settings options so when you launch the app you need to redo any changes you made to the XPlayer app Settings that you had made before. Or if you don't recall even making any changes to the app's Settings than it will just run the same as before.
If there is some issue about the Play Store version of the XPlayer app that prompted you to use a 'modded' (a.k.a 'pirated') version instead, why not just abandon using XPlayer entirely and use a different media player instead? The VLC app is very versatile and includes a really wide range of file types/codecs, and it's free with no ads; the Poweramp app is popular, pay-for (only $7) media player that's also very capable; I like the MX Player app. it has a very extensive Settings menu with lots of options to customize the user interface and optimize hardware and software codec/decoder playback. (free version is really heavy with ads, pro version is just $6). These are just some examples, there are plenty of other viable media apps to choose from.