1. Go to the Junk folder.
2. Check down in the page where it says "Looking for an email? If you don't find it here, check your blocked senders list." and click the provided link.
3. Add and/or remove your blocked senders.
Notice that if you block a sender as spam/junk they can tell you did it (you can thank Microsoft for that), this can stain your reputation, for example in the case you block someone's emails by mistake after subscribing to them, so when they find out they may ban you from their website.
To disable this wonderful feature go to the gear icon on the top right of the page, click "Options", then in "Preventing junk emails" click on "Filters and reporting", from there look for the section "Report unwanted email to the sender" and make sure the option "Don't tell senders when you don't want their emails." is checked.