I`m 23, and played baritone and trombone for 8 years (until I graduated).
Because I missed playing, I bought a flute (since it is not as expensive). I have been playing for about 4 months and am almost all the way through my beginner book, but I cannot seem to play an F (in any octave). It comes out sort of, but usually as a squeak. Every other note sounds clear with good tone.
Could this be something wrong with my keys?

I would take your flute into a repair tech. It sounds like it is more likely to be a leak than anything.

I agree I would take it in because sometimes a leaky pad
only effects one note. I had problems with a screw and it only
effected 2 notes my D & E and got it fixed and then it was
fine

If F doesn`t work, and E & D do, then it is because when you press down the F key the key immediately above it (the `F# key`) is not going down completely. On most flutes there is a screw adjuster for correcting this, attached somewhere to the F key. Just turn it clockwise, probably only a fraction of a turn, until both keys close together.

Some flutes have a tiny piece of soft material, perhaps plastic, glued to the surface that the adjusting screw presses against. These easily come off, which is very likely the case with your flute. If you leave it off, no harm done... there will just be a almost inaudible `click` when you go from playing F# to F.

These bits of silencing material fall off particularly easily on Pearl flutes.

IT HAS TO BE A LEAKY PAD.... i had the exact same problem with my flute until my teacher had to take it to get reapired he noticed the f key had little to no paddding left..

There are three quite different resons for a leaky pad.

1. A pad is not aligned correctly to close level and leakproof with a tone hole.

2. A linkage which is supposed to close 2 or more pads at once is out of adjustment.

3. The membrane covering a pad has been damaged.

The syptoms provided by the player indicate that in this case it is "2", as my last post indicated.