lol dammit ok i'll buy a new micro sd. Do you think the r4 card itself is fake?
http://www.amazon.co.uk/SanDisk-2GB-microSD-Card/dp/B000X4B30O/ref=sr_1_1?ie=UTF8&qid=1365619743&sr=8-1&keywords=2gb micro sd does this one look legit
@Pong2030: but i can delete stuff on it and add new stuff
It's likely you have a 1:1 clone if you bought it recently, some would call this a fake but since it has the same hardware it doesn't really matter. Had you posted here before buying it you would have been recommended to get a different flashcart that still receives official updates, however Wood R4 on an original R4 will do the job as long as you don't intend on getting a DSi or 3DS any time soon.
The reason you can delete and add things might be that your SD card reader/computer ignores the read-only flag, but the R4 doesn't. His suggestion is worth a try.
I can't say if that SanDisk is real or not but you may have trouble with certain games, some games require a high speed MicroSD and on non-SDHC flashcarts an original Kingston SD-C01G or SD-C02G (the japan-produced one) is the best option. There are others that are high speed as well, and there was a good list of them but I can't seem to find it now.
That said, I don't think fake SanDisks are common, but that's just because I never hear of them.
However my experience with SanDisk SD cards are that they are slow. I would suggest almost anything else, perhaps a Transcend card (never heard of these being faked)
I'm not really sure what the best option is other than an original japanese Kingston though, which you should look around for in your local stores (it should say Made in Japan somewhere, NOT on the MicroSD to SD adapter itself as that could be produced in a different place than the MicroSD) as online you never know if they're fake or not, unless you buy from a trusted online electronics store.