What is .dll file ?

If error popping something like - "d3dx9_24.dll is missing, reinstalling can fix the problem". Or "d3dx10_32.dll is missing" and something like that, then install the latest "directx" & problem will be fixed.
The compatible "directx" is probably bundled with game, search directx folder & run .exe or .msi file.
If you can't find then download latest directx from : #-Link-Snipped-#

Even after installing directx any .dll file missing message pops, note down the file that is missing & download it from - <a href="https://www.dll-files.com/" target="_blank" rel="nofollow noopener noreferrer">Download missing DLL files for free | DLL‑files.com</a> OR <a href="https://www.dllme.com/" target="_blank" rel="nofollow noopener noreferrer">Download and Fix Missing .DLL Files - DLLme.com</a> OR <a href="https://www.dlldump.com/" target="_blank" rel="nofollow noopener noreferrer">DllDump - Download free dll files.</a>
And place the downloaded .dll file in system32 folder.

- Installing latest directx will most probably solve the problem in your case,though.

But some errors pops saying "reinstalling will fix your problem" when you are using pirated games & forget to replace original .exe executable files in installed directory with cracked one.

Good luck.

OFF TOPIC - Man,do tell me your review on BOPS2,There are mixed reviews of it.sadly due to upcoming exams,can't play it.
I used to think Treyarch suck badly because COD3,WaW were pretty whack while CoD1,2 & MW series were good.But After BOps1 release they proved they are quite at competition with infinity ward.
Anyways do tell me how is the game,once you're finished.By the way some critics believe it is "best FPS of decade" & many are applauding developers for taking chances.
"Hate it or love it but you gotta respect it". 😁