i think my mira elite st is airlocked how do i fix this?

i turned off the water supply to my mira, cleaned the filter, turned on the shower for a few seconds before i remembered that the water was off, turned off the shower, turned on the water, left everything alone for 30min, turned on the shower and still no water. i have a low flow light at the medium setting but not at the low setting. if its airlocked how do i remedy this. i didnt touch anything else in the unit. the original problem was constant cold water with loud noise

clodagh
March 2013