I cleaned my daughter's flute for her (inside and out). I think I must have knocked something as when she tried to practice all she could get out of the instrument was a squeek. Has anyone any idea what I have done
You're probably exactly right about what happened, but without seeing the flute, it's impossible to know what exactly you knocked loose, or bent, or.... In the future, leave the cleaning to your daughter. Hopefully her teacher (if she has one) has gone through the proper procedure for cleaning with her. If not, ask a more advanced flutist to demonstrate and describe what must be done (and what should be avoided) when cleaning your flute. For instance, you never want to grasp around the mechanism (keys), you shouldn't try to clean under the keys if the implement you're using won't fit, etc. In order to get the flute back in working order, you'll need to take it to a tech who can find and right the issue(s). It was a nice thought, but flutes (and other instruments) can be rather delicate, so it's best to leave their handling to those who are trained to take care of them. If your daughter has not been taught how to care for her flute, please feel free to let us know, and we can lay out the basic bits of knowledge she'll need.
You may well need to repair technician to fix this but two quick things to check:
1. Can she blow the mouthpiece (without the body attached) as normal?
2. Are the springs for the trill keys nearest the mouthpiece closing those keys properly. If you are unsure, hold them closed (with light pressure) while she plays. If this is the problem and the springs are still present, then her teacher should know how to put them back to their proper position.
(And don't feel bad about it, even my daughter when cleaning her flute has dislodged these springs).