Re-verify game files (Fix #1), then reinstall SKSE if used.
When encountering this error, your first instinct might be to search for a quick download link online. However, downloading individual DLL files from third-party websites is highly dangerous. skyrim legendary edition steam-api.dll download
Before trying anything else, check if your security software has mistakenly flagged the file. This is the simplest fix and will work in many cases. Re-verify game files (Fix #1), then reinstall SKSE if used
Your antivirus software likely moved the file to quarantine during a system scan. Open your dashboard. Navigate to the Protection History or Quarantine section. Re-verify game files (Fix #1)