I must have accidently hit some button but I do not know which one and so can't see to go back

A track now has three levels on it, the top one has A in it, the middle one a sort of X, and the bottom one a B.

Also the preview screen now has two clips showing in it, there are some greyed out clips and some sort of red vertical divider between a couple of clips.

What has happened?

I am stuck...how do I go back?

Renton

Somehow you have activated the "Expand Track Layers" option. Right click on the head of the track in question and come down the drop menu to where you see a check mark tick on the "Expand Track Layers" option and uncheck it and you video track will go back to the default single track that Vegas opens up with.

The old A-B editing paradigm with transition on the 'X' track is still liked by many older editors who grew up working with this type of layout in very early NLE software. Premiere was one of them in its early days.

Chris Young
CYV Productions
Sydney

I must have accidently hit some button but I do not know which one and so can't see to go back

It is numpad button 5 that svitch to "Expand Track Layers". Press it once again.