is there a way to get the whole chat content from one of the channels from yesterday for example

mIRC has a logging feature that is on by default, so you should be able to see the log of your channel by typing //run $logdir in any mIRC's editbox, it will open the directory where mirc store the logs

Note that if you have logging disabled, you will not be able to retrieve the log. However, *someone* in the channel likely has logging enabled and you might be able to get the log from them.