Have you lost your SDCard storage space?
Is your SDCard size now about 200kb?
But if you can't find the answer... Here is the solution
The reason your SDCard is showing the wrong size is that you've flashed a rom that is not meant for the hboot on your phone.
But before you start you need to know what hboot you're on. Get the phone into bootloader and it will show you what hboot you're on (If you don't know how to do this by now, give up and get an iPhone lol )
1. Download ESfile Explorer from Play Store and go to settings and then root settings and give it root privileges. Once thats done go to root of phone and go to /system/etc and find a file called vold.fstab and open it with a text editor and find this line
dev_mount sdcard /mnt/sdcard 34 /devices/platform/msm_sdcc.2/mmc_host
now for 1.25 hboot you will need to change where it says 34 to 33
and for 1.28 hboot you will need to change where it says 33 to 34
Save the file once done and reboot phone and voila you should have your sdcard back if you've done it right
2. Download the files I've attached for which hboot you are on and then make sure usb debugging is enabled in settings/developer options and plug your phone into computer. Then download the ADB & FASTBOOT zip attached and open zip and drag the folder onto your desktop, open the folder up and then open the zip for your hboot and drag the vold.fstab into the ADB & FASTBOOT folder. Double click on runme.bat and you should get a command prompt window pop up. With your phone connected you will need to type this
adb push vold.fstab /system/etc
Once rebooted you should have your SDCard back
3. Probably the easiest way, just download the right hboot zip and get the vold.fstab from it and put it in the rom zip you flashed at /system/etc and flash it again... Or edit the one that is already there...