What version of android do you use ? if you have prior to 2.2 you can't install applications to sd (you can use link2sd however).
You can still store music, videos, maps etc....

 

Link2Sd is an app that you use to copy to apps to sd card, you have to partition your sd card and link2sd essentially moves your files over to the sd card but creates a "link" so your phone still thinks it's installed on internal memory, just the link has virtually no size
Tutorial - [App] Link2SD - xda-developers

 

Do you need a rooted phone for this?

 

Yes you do, if you are running Android 1.6 than this quick guide to rooting your phone would work
How to root your LG GT540 - Android @ MoDaCo

 

I mistakenly partitonedy SD card through ROM Manager from Android market without knowing its circumstances..... And Now, I can't access the memory of my SD Card...... I cant add anything to my memory card.... Whenever i try doing so..... It says not enough memory but the phone shows a lot of free space on SD card.....


Someone please help me!!!

 

Put the SD card in your PC/laptop (connecting the phone using a usb cable will work as well) then go to start and type Disk management, the click "create and format disk partitions" go to your SD card right click a partition and select delete partition, do this with all partitions the you will have a block of unallocated space, then right click the unallocated space and click create partition and format it with FAT32 (you may get a few blocks of space, in which you will have to merge multiple partitions)

If disk managment doesnt work you may need a third party disk managment software, just google for some and read reviews to make sure its legit, I'm pretty sure windows disk managment will not find ext partitions.

Also on your phone there is an option to fomat the SD card, however I dont think that will re-partition it as well.

 

Hi , I already root my device LG GT540 and i already use the Link2sd and it works smoothly and fine , my problem is when i partition my sd card i cant move music files or any files from my pc its says that my sd card is write protected and the other partition for my apps doesn't show up.

thanks