This week i tried booting my Raspberry Pi, but this showed up:
end_request: I/O error, dev mmcblk0, sector 148225
mmcblk0: error -110 transfering data, sector 148226, nr 254, response 0x900, card status 0xb00
Internet did not gave me solution, but (for the first time) Windows did!
It turned out that as simple as pushing the SD card in Windows Vista/7/8 computer can already fix your SD card. Just use the windows error checking option (right click on the SD card -> properties -> tools -> press "Check now" under error checking) to check the filesystem for any corruption. Once you checked it, it may even say that there were no errors found, but it fixed the boot problem.
In the case that Windows doesn't even recognize your SD card, you can still reformat your SD card via Disk Management. Hit the start button and paste
diskmgmt.msc and hit enter. In this utility you can re-format disks which are not recognized by Windows Explorer. This solution doesnt allow you to save the contents, but with a format you can atleast re-use the SD card.
Let me know if this helped you!
Some other topics: