Welcome to the forum.
Bit late now but a basic rule with any software is to take a
backup before opening a file with the new software.
There is a solution which if you are lucky will give you your
project back intact, at worst you will retrieve it with a bit of
work to do.
Take a copy of the project as it is now.
With the copy delete the CPD and XPJ files. Then right click
the HHP file and use Open With | RH HTML. If you have not removed
the trial version, there will be two versions showing, use the one
with the orange icon.
See the topic on my site about opening projects for details
of what you might have lost.
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