It may sound obvious, but look directly below you.
I was once on a cross-country and couldn't see the aerodrome I was using as a fix.
Due to shadows and light I did not see the airfield as I approached it in a low wing SEP.
As soon as I dipped the wing to turn in an effort to fix my position (and therefore go no further) lo and behold I was directly above the fix!
Don't panic and follow the good advice proffered elsewhere in this Thread.
KR
FOK
