Hello,
Please follow the instructions below to reset sync.
1. Disable automatic syncing in EndNote preferences, and restart EndNote.
2. Delete all references and all groups from EndNote Web, with the exception of Shared Groups and ResearcherID Groups.
3. Empty the Trash both in the web application AND in EndNote desktop.
4. In EndNote desktop, add this to the end of your E-Mail Address in the Sync preferences: #!resetLocalSync
Note that this is case sensitive – #!resetLocalSync NOT #!resetlocalsync. For example, if the email address was john.smith@thomsonreuters.com, you would change this to john.smith@thomsonreuters.com#!resetLocalSync
5. Click Sync.
6. EndNote will then appear to authenticate and return the prompt: “A Sync library can be linked to only one account. Do not proceed unless you intend to break the link to the original account.” This happens because we tricked EndNote into thinking it authenticated against another user. Click OK, and EndNote will purge any knowledge of a previous sync.
7. EndNote will then display a message, “Your local sync state has been reset. Please re-enter your E-Mail Address, restart EndNote, and Sync again.”
8. Restart EndNote.
9. Open the Sync Preferences, enter the correct username/password in and setup the automatic sync settings. Continuing with the example used above, re-enter john.smith@thomsonreuters.com as your email address in the Preferences.
10. When you next click Sync, you will once more get “A Sync library can be linked to only one account. Do not proceed unless you intend to break the link to the original account.” Click OK.
11. You will be prompted to make a backup, which is recommended.
12. A complete sync will then begin.
I hope this helps you out!