Try to uninstall and install MT4 once again.
As to Windows 10 so I collected some posts so it may hlp (I hope) - read this post: https://www.mql5.com/en/forum/9950/page72#comment_2633170

- 2016.06.30
- www.mql5.com
And read the following thread: MT5 platform won't startup after installing the Windows 10 Spring Creators Update
Hello.
Thanks for the help. In fact, I installed MT5 just to test and it works fine. But MT4 does not launch. Unfortunately, my accounts are not recognized in MT5.
This was from MetaQuotes from some time ago -
Forum on trading, automated trading systems and testing trading strategies
Update of MetaTrader 5 terminals for compatibility with Windows 10 April 2018 Update
MetaQuotes Software Corp., 2018.05.02 11:17
Update of MetaTrader 5 terminals for compatibility with Windows 10 April 2018 Update
Today, we are releasing an update for desktop terminals, which fixes compatibility issues on the latest Windows version.
We strongly recommend that you install this update.

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Hello.
I have downloaded MT4 from both BDSwiss and Alpari. They were working perfectly fine, but I reset my laptop and fully reinstalled Windows 10. Now they do not work. They do not give any error message, simply, they do not start. When I click on the program's icon the clock shows for about ten seconds, then nothing, nothing at all. No warning, no error, nothing.
I have tried to run it in Administrator mode, same thing. I tried to run the Terminal.exe program as compatible with past Windows versions, same thing.
MT5 runs perfectly fine, but my accounts are not recognized since they are MT4 accounts.
Is there any log where I may find out what is happening? Has this issue already been detected and fixed?
Thanks.