Memoriefull my memorie isfull and i whant to delete every thing but i can so what can i do

I would try a firmware upgrade first from Sandisk's website, but if that fails to resolve the issue:
1.       “I can’t load any more songs into my mp3 player” or “An incorrect number of songs show up.” (MEMORY/FORMATTING ISSUE)
Sometimes, you can’t load any more songs into your player because, well, there just isn’t any more space left on your player.  Mp3 player product documentation does not actually list the actual amount of memory that you can use in your player, and it doesn’t list the actual number of songs that you can realistically fit on your player.  Every mp3 player needs a certain amount of memory space to operate and firmware upgrades decrease this available space – so, your 2GB mp3 player actually contains only 1.7 or 1.8 GB for music and other media files.  The mp3 player that says “can hold up to 1000 songs” may only hold 400 songs – the product documentation assumes that you are loading a 1-minute song in the lowest possible quality format – not very realistic.  A single 30-minute audiobook, speaker file, or video can seriously bring this number down.
Other times, however, you are experiencing a formatting issue or memory corruption.  If you plug your mp3 player into a computer that has an NTFS file system, and then plug it into a computer that has a FAT32 file system, you may experience this formatting issue (file system/formatting issue).  Similarly, this will happen if you plug an mp3 player into a computer running Windows Vista, and then plug it into a computer running Windows XP (operating system/formatting issue).  Or, if you plug your computer into a PC, and then into a MAC (PC or system/formatting issue).  Or, if you plug it into a computer with Windows Media Player 10, and then into a computer running Windows Media Player 11 (software/formatting issue).
There are three other possible ways to resolve this issue – firmware upgrade, recovery, or reformatting/formatting.  WARNING: All of the methods suggested below will erase all of the songs off your player – back up all files first by transferring them to your PC.  It is best to do a firmware upgrade first – these are available from the manufacturer’s website.  Recovery methods vary by mp3 player – check with your manufacturer’s website or user’s manual for details.  Many mp3 manufacturers have their own recovery tools – the Sansa Recovery Tool, a Philips’ Device Manager Repair, or the Apple Recovery Tool for instance.  Other times, there is a specific button that triggers the recovery mode – volume + for most players, REC buttons for others, play for others, and skip forward for still others.  The general formula goes something like this, although you may have to substitute another button for “volume +”: disconnect the player from the computer, turn it off, hold in the volume + button, and reconnect the player to the computer while holding the volume + button in. Keep holding the volume + button for an additional 5-50 seconds. Windows should eventually go into recovery mode and revive the player- it will pop up a window that says Found New Hardware Wizard.
Before proceeding with a format or reformat of your mp3 player, check with the manufacturer first.  On many players, a format or reformat along the lines suggested here will override your mp3 player’s native formatting and render your player unusable.  Transcend’s T.Sonic player is especially susceptible to this problem, and should never be formatted.  Also, the instructions below are for Windows-based PCs, not for Macintosh.  There are two ways to format an Mp3 player - one on the computer itself, and one in Windows Media Player. Both methods will end up erasing all the songs on the player, but the player will be "good as new" after that. Sometimes reformatting in this manner will override the player's native formatting and cause problems - this can be reversed in some cases by updating the player's firmware or reloading the firmware. Firmware upgrades are available from most manufacturers' websites.
WARNING: The following procedures will erase all songs on the player.
Check if the file system is NTFS. If yes, format it to FAT or FAT32. - Connect player to computer, double-click my computer, right click on icon of mp3 player and select format. This only applies to Windows-based computers.
You can also format the player in Windows Media Player itself:
Connect your Mp3 player to the computer and open Windows Media Player. Click on the Sync tab. Pull down the drop down menu underneath the Sync tab by moving your cursor over the Sync tab and left clicking on the little black arrow underneath the Sync tab. Highlight "name of Mp3 player here 1GB" (wording may vary slightly), and then select "Format." - this should erase everything.

-Tha Mp3 Doctor