Blank CD rewritable

I have 2 cd roms : I ordinary cd and a cd/dvd rewritable.
For quite a while now I have been able to put a blank cd into the cd rom and it has shown me that there was nothing on it, but now it tells me that is inaccessible.

With the cd/dvd rewritable I have again put a blank cd writable in it and it asks me how to run either as folder in Windows explorer or a win amp file. I click for a windows explorer and it goes onto the f drive(where my cd/dvd rewritable is ) and shows me that there are no files in it. I could then copy and paste a file on to it(like a floppy drive) once again I am unable to do this and it tells me that it is in accessible.

Both cds run when there is data on them, but not when they are blank.

I would like to copy files onto a blank cd writable again.

Can you tell me what is wrong and what I can use

John