Failed to load config bundle error  

calling @neophyl

That looks like file corruption - take a copy of your configuration directory and investigate ... 

Do you have any of the gcode files produced with these presets?  If so most of the settings you've lost will be in them and can be re-imported.

@neophyl is probably the most experienced in this area on the forums - @neophyl are you on line?

Cheerio,

RE: Failed to load config bundle error

Sometimes 🙂

PrusaReasearch.ini is the default main store for the built in prusa profiles that the wizard uses to install from.  It wont contain any of your custom profiles.  If its not loading with that sort of error then yes it does sound like some form of corruption.  
That particular file starts with the following

# Print profiles for Prusa Research printers.

[vendor]
repo_id = prusa-fff
name = Prusa Research
config_version = 2.3.3
config_update_url =  https://files.prusa3d.com/wp-content/uploads/repository/PrusaSlicer-settings-master/live/PrusaResearch/ 
changelog_url =  https://files.prusa3d.com/?latest=slicer-profiles&lng=%1% 

As you can see its more of a descriptor block.  The first 'real' line is the repo_id = prusa-fff which is what your posted error message seems to point at.  The first block is then followed by all the actual base profile info for all the prusa based printers, filaments and print profiles.  Its a pretty large file naturally.   All those various vendor bundles are part of the install data and get updated periodically when it downloads new versions (if you allow it to).  Download PS again and the file should be in there if you extract (basically download the github release, unzip it to someplace and you can go through it to find the correct file.   

If you were to backup your current folder so you have still have them someplace safe and then replace the problem file with the newly downloaded version that might get PS working again.  And if you can get it working then you can see if your custom profiles are then accessible.  

All your user data is usually under a user folder.  Not sure of the location on a MAC/Linux but for windows its along the lines of Users>username>AppData>Roaming>PrusaSlicer . 

From there there are folders with your installed/configured printers, filaments, print profiles etc.  As well as PrusaSlicer.ini that stores things like most recent files, screen positions, preferences etc.  So your profiles should still be there so even if you have to nuke the install completely if you take a backup before doing so you can probably add them back with a bit of effort.

There's a cache folder in there that has the vendor ini files.  It is likely that one that has the problem.  However there's also a folder called "vendor" and that ALSO has a copy of the prusareasearch.ini in it (at least for me it does).  Not sure why it has multiple copies really but its something to be aware of.  Worth checking both.

If you can get PS running though with your profiles still intact, the very first thing you should do is use File>Export>Export Config Bundle (either with or without physical printers).  That will export to a single file all your non standard CUSTOM profiles. 
It wont export the built in ones though.  As you can get those by running the wizard at any point. 

You can then keep that exported config bundle safe elsewhere on a suitable backup medium.  With that you can always load your custom stuff on any install on any computer using the Import Config bundle option.  Will help if you have future issues.