It might help to know what kind of phone it is. Does it run a specific operating system?

There is probably an option somewhere to format the memory card while it is in the phone.

First of all, I'm sorry if this is not in the right area, but I couldn't find a more suitable place. Please move if necessary.

Well, I bought this cellphone from the store, and I decided to put in some sounds. I connected my phone to the USB port in my computer, and I mistakenly formatted it into NTFS. Afterwards, I found out that phones only support FAT drives, so I converted it back to FAT and put in extra files.

When I opened my phone, I looked at the "File Manager," tab, and I saw the memory card, as usual. But the phone memory wasn't there!

I tried to send a message, but whenever I went to "Write Message," a message pops up saying, "Invalid file system."

It's as if the phone has turned into a mere storage device. I can't send a message, but I can call though. Can anyone help me with this?

P.S.:
My cellphone brand (my|phone) is exclusive to my country, the Philippines, so I'm afraid any more specs wouldn't help greatly. But, if by luck, someone who is very knowledgeable from my country would stumble by this post, then I would feel so happy.