External hard disk changed from "Read and Write" to "Read only"

Hey guys, little problem here.
I have an external Transcend HD, which has been working perfectly fine for around 5 months now. It is NTFS, and I use NTFS-3g and Macfuse. Been running fine. Was able to read and write.
Suddenly I am only able to read though. I go into the "Get Info" pane and the option to choose whether I want to read and write, or read only is gone, and all that it says is "You can read only". Any help or advice to getting this back to read and write is really appreciated. I really need this disk.
Thanks

 

Thank you for your response. Repair Permissions is greyed out in Disk Utility, so I cannot click it. Also, "Verify disk permissions" "Verify Disk" and "Repair Disk" are also greyed out. Basically I cannot do anything to the disk apart form erase it and reformat in Disk Utility.