Can acute kidney failure recover even if the kidney shrunk and has igan?

Depends : If your ultrasound shows shrunken or small kidneys then there could be considerable fibrosis which is not reversible.

Probably not: Once kidneys have become small, they are very diseased. If the acute kidney failure does recover (which we would certainly hope happens) it is unlikely that normal kidney function would be attained. If sufficient recovery to stay off of dialysis does happen, it is important to treat those kidneys as gently as possible with excellent BP control and avoidance of injury from meds or contrast dye.

Not likely: Once the kidney has become smaller there is scar tissue within that represents irreversible damage, regardless of which disease is involved. If some kidney function returns it is not likely to be normal and careful attention to preservation of the amount that is retained will be extremely important.