I made a folder on the YH820 called system renamed the .mi4 file in this rockbox http://build.rockbox.org/ to FW_YH820.mi4
The URL you posted contains links to all players we provide binaries for. Therefore I'm not able to see which one you used.
so where am I going wrong this is very hard to understand for me as never done it before
I don't know since I don't fully understand what exactly you did. I really suggest writing proper sentences and using punctuation, as otherwise it's rather hard to understand it. I'm not willing to spend too much time trying to decrypt your messages much longer. Punctuation is something that even works fine for automatic translations.
Where have I said I did the above I have not placed rockbok files in system folder the only thing in sys F is the firmware which I said above
No. You put a Rockbox file into System.
Rockbox comes in two parts (btw, this is described in the manual): the bootloader and the main binary. The bootloader is (for your player) a single file using the extension mi4. The main Rockbox binary is a folder named .rockbox that does contain various other files and folders. It does ALSO contain a file using the extension mi4. This is a fundamentally different file to the bootloader, and that file requires the other files in the archive as well.
I have made a folder on the YH-820 called system placed that samsung firmware into it. also unpacked the file here Get the Rockbox build from here: http://build.rockbox.org/ (Samsung YH92* only as of now) or compile Rockbox from SVN on your own. Then extract rockbox.zip on the Samsung.
to samsung too so have a .rockbox folder and a system folder on the samsung only. booted it up nothing all i get is rebuild database with recovery utility. so i placed folders from rockbox loose on samsung including system folder nothing too
I really don't understand this. Which file *exactly* did you unpack? What is the thing about the recovery utility you're talking about? Why do you get something with this recovery utility when starting up the player? That tool runs on the PC, and starting the player doesn't involve the PC at all.
Since I don't have that exact player I can't give you exact instruction. Judging from a different player (that also uses the mi4 file format) it should work like this:
1. Download
http://build.rockbox.org/data/rockbox-samsungyh820.zip2. Create a folder called "System" on the player. If your player has drive letter F: in Windows, this will give you a folder F:\System
3. Open the downloaded zip file. Copy the folder .rockbox from the zip file to the player. This will give you a folder F:\.rockbox
4. Change into the folder .rockbox and copy the file rockbox.mi4 to the System folder. You'll now get a file F:\System\rockbox.mi4
5. Rename F:\System\rockbox.mi4 to FW_YH820.mi4. You'll get a file F:\System\FW_YH820.mi4.
6. Safely eject the player from Windows (this is important!). The player should now reboot, if not shut it down and power it up again.
This will install Rockbox without the bootloader since there is no bootloader binary available on the download server. This should work fine though, but you loose the functionality to boot the original firmware.
Alternatively, you can also go back to the original firmware. In that case skip steps 1, 3, 4, 5, and 6. Instead copy the original firmware file you can download off the Samsung website to the System folder and name it FW_YH820.mi4
3.