I've got a Proline TVC140, without a remote. The screen is just blue, the video is OK, that plays. But I can't tune any TV stations in with no remote.

I don't have an answer for your question. But, I care that your question gets answered. By my posting a reply now, your question will get moved more towards the top of the list of questions needing answers. Hopefully, someone will come along soon with the expertise to answer your question.

You can buy a cheap universal remote and program it to this TV...

The one thing you need to do is put instructions in safe place...

Don't lose the remote and don't lose instructions!!

Not sure of your exact TV, my one TV you can't, no buttons, if there is no buttoms to move channel up and down or sound, there is just no way.
The universal remote will be your best bet.