Procyon gave you all athe information you need....but I would add that many MMM buyers, at the basic level, often times relate they have very little, or none, computer type skills...and thats OK, we all started somewhere.  I advise people to make up a USB backup of your soundpool and VST stuff, just in case.  That way, you will always have a "fail-safe" backup.  The two most asked questions in Knowledge Comm. are !.  Can I sell my stuff I create ? and #2 is " My soundpool is gone...missing....messed up and all I did was ....."  They are on your hard drive, but some people don't know they even have a hard drive.  Hope this helps.      

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It seems I have to interfere for further help.

Please read the pdf tutorial you will learn something.http://www.magix.info/us/soundpool-problem-and-solution-faq-for-mmm-16-premium.online-training.70780.html

If all else fails.....every soundpool has a name...HipHop2, and so on.  You have to figure out what soundpools you lost.  These names are also the File Names.  For each file name you do a Search....are you still with me ?  When you find it....and you will....write down iln whaat folder and you may filnd lost soundpools ln the same folder.  Once you  have found all your missing soundpools, go to Media pool open soundpools and click on Add...and tahen you will have to direct your computer to the folders you found and add the missing soundpool.  If after all this help you are still somewhat lost....go directly to Jail, do not collect $200 and serve your time