my problem is that I can't save my samples/multisamples.When I switch of my keyboard it seems like all my samples are deleted!!! (I have a ram-16MB and its memory status is 100% free) help please!!
This is normal behavior. Like a computer, if you switch it off, the RAM memory is deleted. On a PC you have to load it from the hard disk again, on your synth you need to load it from some media (floppy/multimedia card).
(see it that every time you turn on your computer you also have to load your apps and documents).
There have been requests to autoload samples it after startup but this is never implemented (also probably because it takes time), especially with floppies. On the Kronos it can be autoloaded but it has a SSD. On floppy and even multimedia cards it goes a lot slower.