You can try....
If you do, the minimum you must do, is to go to Tools > Configure Build Lazarus
and do a clean build.
Even better, find and delete all *.ppu and *.o files in the install dir.
It may or may not work
Your settings are stored in the "primary config path". They are not removed by the installer (The uninstaller has an options, but it is not set by default.)
Where your pcp is? Menu: View > Ide Internals > About IDE.
Also instead of an uninstall, you can delete all the files in your install folder. That will definitely be enough.
So if you did not copy any data into your install dir, then that is good.
One thing I am not sure: The packager directory in the install dir has "package links" (the location of packages) *.lpl .
I do not think any new files get created there, but in case.... copy it.
Or better yet, rename the existing dir, then install. That way you have a backup.
The list of which packages you installed should be in the PCP dir. (with the config).
After installing an update you need to rebuild your IDE once, for the packages to be installed again.
Should you get any complains a package can not be found (unlikely), then open the package from the package menu, close it again, and retry. The IDE will then know the location.