Reinstalling windows has nothing todo with libcurl.dll.
To get that file you update to official latest version (120) then you should have it. If you still dont have it then its mostly a crap solution of antivirus software, f.e. avast and avg. If it still shows an error but a different one then you may not have installed latest windows update and/or no visual redist package (microsoft).
Just checked it again, when i update, i get libcurl.dll.
What often helps because mostly windows UAC permissions are the reason:
1. Create a new folder with any name on desktop (i call it HSR).
2. Inside that folder, copy Update.exe and run it. This will update to a full client inside that folder.
3. libcurl.dll should be present (If not, turn off antivirus and try again from step 2)
4. Override client executable with preview client.
5. Start playing using old launcher or through directly starting client.
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