Micro SD won\'t let me add new files (nor delete)

[abooth]

my micro sd wont let me delete or put music on it through my phone my phone wont read it and it asks me to format but then says err any help?

 

[electrontau]

what size is the microSD? Will the phone support it?

 

[abooth]

its a 4 gig and i think so its a sandisk my phone is a samsung gravity t

 

[WyomingKnott]

A) Does it work in any other device?
B) Has it ever worked in any other device, or is it new?
C) Is is MicroSD or MicroSDHC? I don't know about the Gravity, but some phones will not read the MicroSDHC cards even if they fit within the phone's memory size limit.