Before you do anything else, if you have a device(s) that might have the vault logged in, disconnect it from the Internet (put it in airplane mode, unplug its network cable, etc). Only after that is done and you confirm that you can not access the Internet with a web browser, check if you can access your vault. If you can, export your vault (password protected or unencrypted are both OK, but do NOT use account restricted). Having a current backup will keep things from getting worse and will dramatically reduce your stress level.
After that,
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Type your password into a text editor and copy/paste it to the login screen while ensuring you do not grab any leading/trailing spaces.
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Check out this conversation: Master password is not working
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Check out this link: I Forgot my Master Password | Bitwarden Help Center