if the audio/video is out of synch, in Sony Vegas, look near the top in the toolbar for an option for "Ignore Event Grouping". This will allow you to adjust your audio without having the video to move with it.
you can also increase the height of your audio track and zoom in. It's easier to re-align your audio/video if you find a scene where there's a sudden impact sound. like a box hitting the ground, a door closing, a footstep.
It's mush easier to synch up if there's a strong visual cue to go with the audio cue. especially, a part where the scene has no music or much background noise. even dialog can be useful if you pay attention to the lip movements. Vowels are dead giveaways.
Frame by frame stepping will make it much easier to find out which frame should have the audio synched up as your reference point.