Which memory card did you format? The external or the internal? I think I read somewhere on XDA where formatting can lead to SD card corruption.
If its external SD card, plug it to your computer and in go to windows command prompt and run it as administrator.
Then type: DISKPART
Then type: LISTDISK
Then look at the list and see if your SD card shows up.
Then type: SELECT DISK #
The # need to be the number of the SD disk from the list that came up
THen go: CLEAN
This will wipe everything.
THen go to disk management and format the SD card. It should be usable now.
Or follow this:
http://www.sevenforums.com/tutorials/52129-disk-clean-clean-all-diskpart-command.html
It got pictures
If it is internal. Then use ODIN -> flash CWM -> In CWM wipe everything and install ROM AND Flash GAPPs
Also When the PC can't see the phone its usually down to 2 problems:
1) Driver
2) USB 3.0 port. For some reason, mostly drivers, Android phones don't really support USB 3.0 in fastboot mode.
You can install KIES or google around for samsung drivers.
For 2nd problem plug it into usb 2.0 port.
And I also saw in your previous post of using Heimdall.
Failed to access device could mean:
1- You are not in ODIN mode. : "boot the Galaxy S III (International) into download mode by holding Home & Volume Down & Power. Accept the disclaimer on the device. Then, insert the USB cable into the device."
2- Driver is not installed properly or not working
3- USB 3.0 port
Seriously, Heimdall is for people who been using linux since 1990s.
Use Odin to flash CWM recovery and boot into CWM to install rom.
Android has 3 thingys: Flashing mode (Samsung calls it ODIN mode), Recovery and Rom.
Recovery is where android tries to recover itself.
CWM replaces this recovery with more awesome recovery mode with more functions where you can do back up and flashing roms.
Google how to boot into recovery because its device dependent. Usually power button + volume down key.