Recently I had problems with my SD card not mounting in Recovery mode. This is how I fixed it: DISCLAIMER: NEITHER DROIDFORUMS.NET NOR MYSELF ASSUME ANY RESPONSIBILITY FOR DAMAGE, OR LOST DATA. 1. First and foremost BACK UP YOUR SD CARD! I will not be responsible for lost data. a. Backing up data: Either mount your phones SD card to your computer via USB cable or with an adapter (I keep an adapter handy for when I test partitions because the phone wont always read the SD card properly, these can be had for cheap at Walmart) b. Select EVERYTHING (Ctrl A) on the SD card. c. CUT (ctrl X) the files and copy them to your desktop or whatever file you choose to put them in. Double check to make sure ALL files are copied over and nothing is missing before proceeding! 2. Formatting: Once everything is copied over and your satisfied its all there you need to format your SD card. There are several ways to do this: a. Windows: right click on the icon on your desktop for your SD card 1. Select FORMAT 2. DO NOT PARTITION YOUR CARD> Android uses FAT(32) file system, so make sure to format it with this! 3. DONE! b. Phone: Disconnect your phone from the computer. You wont need it right now. 1. On your phone: MENU>SETTINGS>SD CARD & PHONE STORAGE. 2. Select UNMOUNT SD CARD 3. Select FORMAT SD CARD and wait for this to complete 4. DONE! c. UBUNTU 10:10 (this is what I use): Open disk utility (SYSTEM>ADMINISTRATION>DISK UTILITY) 1. Click on the SD card in the menu on the left, under removable media. 2. Unmount the SD card, this wont work otherwise 3. Select FORMAT DRIVE/VOLUME above the VOLUMES indicator. 4. Select NO PARTITION under the drop down menu and then click OK Under the VOLUMES indicator: 5. Format (Again, Android uses FAT(32) file system. 6. Remount the SD card 7. DONE! Hopefully this fixed it for you! DONT FORGET TO ADD YOUR FILES BACK TO THE SD CARD!