Question: To add subtitles to a single file I use the following command:

`mkvmerge.exe -o g:\movie01.mkv --default-track 0 --language 0:pl movie01.mkv movie01.srt`

**Where:**

`movie01.mkv` is the name of a video file

`movie01.srt` is the name of a subtitle file (it is always the same as the video file)

`g:\movie01.mkv` is the output file

**How do I run the above-mentioned command for every file in a directory?**

Answer: 
No, this is the 32Bit Explorer.exe on a 64Bit Windows. This is called [Windows 32-bit on Windows 64-bit (WOW64)](https://en.wikipedia.org/wiki/WoW64) to be able to still run 32 Bit applications on a 64 Bit Windows.

Don't worry, your PC is fine.
So, as it turns out, it was a virus.

I rebooted my Windows after scanning it to find that it had triggered a `diskpart` on my machine, wiping my hard drive.

I took it to the local computer store, and the guy that worked there said that it would of caused it. (He somehow managed to check logs that were on my motherboard.)

Virus Total said it was a virus and Malwarebytes said it was a virus, but I couldn't remove it.

Ah well, i'll just switch to Linux then :D