Hi
Can't think what you have actually done. It sounds a bit odd from your description. My best advice to anyone creating a project is to regularly save your progress. Just click "File" and then "Save Project File" or "Save Project File as" This will ensure that if you cock up (or your system goes mad) you can easily load it back again.
What has actually moved? If the program is working correctly you can't "Cover" the data on another part of the sequence, only displace it. You can independantly move unlinked sounds clips or overlays however.
Start by switching into Storyboard mode. This will enable you to see what clips are where in relation to each other and you won't need to zoom in as all the clips are shown as a single frame.
Now you should be able to see which video clip/s are out of place and you can drag and drop them back into position.
If you have unlinked the sound from these clips you might have more of a problem...1) to recognise them and 2) to get them back into position. You can still drag and drop them however. You can check the sound clips by playing them in the left hand preview pane. The difference in this mode is that sound clips are compressed visually to match the frames which, of course have differend playing times.
I can't say why sections of your sequence play in milliseconds unless you have altered their playback speed. Check the value shown in the small box under the frame. Has it the correct value? Click on a clip that seems to play too fast and then the Effects tab. Open the "Speed" effect (V2.41) and then verify it is set to 100%
The other thought is that you may have inadvertantly Split a bit of the clip off and or dragged one or other of the clip ends in, and so shortening the clip. To set this right (if this is the case) then you can simply go back into Timeline mode, click to select the clip that is too short and drag one or both ends out to extend it back to its full length. Note that even if you spit a clip and delete one of the bits, it still remains as an invisible "whole" clip and can be easily restored as noted above.
Nat