How to get sound to one channel


I’m a beginner and I have made just my first recordings.
I have one project where is couple channnels and there short audio recordings (about 15-20 sec).
Yesterday I made new channel where recording is much longer. I can see that recording is ok but I can’t hear that channel. But I can hear other channels in same project which I recorded earlier and I manage to do other shorter recordings as well yesterday which I can hear.

There is probably very simply answer and sorry about this beginners question.

Have you got the monitor button pressed on that channel? It turns brown when activated

I manage open the channel for a little while. Then when I open 2 channels I lost the voice from the both channels. Sometimes I cant get voices from the earlier recordings work either.

I have started to doupt that I don’t have enough power in my windows computer.