How to backup contacts, calendar and tasks from HTC One M8 Windows Phone
In our guideline we will introduce PhoneCopy.com service which supports many phones from almost all manufacturers, including HTC One M8 Windows Phone, and can be easily used to synchronize data between two or more devices.
Download the PhoneCopy application from windowsphone.com. If you do not have a PhoneCopy account yet, press "Register new account" and create it by filling in "Registration" and then press "Sign up".
If you already have a PhoneCopy account, fill in your username and password. To export your contacts, press "Export to PhoneCopy.com". If you want to upload your merged contacts back to the same Windows Phone 8.1, it is necessary to delete all contacts there first.
Now you have all your contacts backed up on PhoneCopy and you can edit all your contacts in your online account. If you lose your phone or the stored data, or if you just run out of battery, you can see your contacts online.
Some additional tips:
You can easily remove duplicate items among your contact list or SMS messages. Just go to the Contacts (or SMS) section and choose More Actions -> Search for duplicates. Detailed wizard will help you to solve this kind of problem easily.