I cant get into internet recovery mode.

I have this funky old pre owned 2008 mac pro, and im trying to get into internet recovery mode, but i cant.

Currently this mac powers OS X El Captain. Every time i turn the mac on it starts up in recovery, and i cant install mac os as it says "this item is unavailable". I have the recovery hd drive but it wont show up in my drives, i have 5 spare drives and wish to use 1 but they are the ones that say the item is unavailable. Im not too sure if this is a big issue but im using a wireless keyboard and/or my microsoft keyboard to try to get to intermet recovery. Obviously ive not set the keyboards up to sync but they type fine. I press the said keys command alt and r and still nothing happens but the apple logo and the standard loading screen for utilities etc. Ive looked everywhere and tried everything, yet cant seem to find a solution. Maybe someone can walk me through it? Oh and all the other drives are completely empty by the way. (Apart from recovery hd).