Hi,
In https://account.microsoft.com/ site in bottom "contact us" option is present, from there you contact support team.

Support works in 2 level.
1st level they would try to repair or uninstall/install or check the license validity period from your laptop by taking remote.
1st level support is basic troubleshooting.
2nd Level is the technical team, they have access to back end.
When you are contacting support, in beginning itself inform the support team that all the basic troubleshooting has been done (like online repair/uninstall/install/license validity etc..), so they will transfer to technical support team.
My issue was resolved by 2nd level support team.
When we contact support always we will be forwarded to 1st level support team, only when we explain things clearly they will re-direct support to 2nd level.
Make sure you have the following details with you when u approach support
- Invoice of u laptop.
- Image in u laptop stating "Office Home & student Don't forget to activate".
- Have good internet connection.
- Before starting the support, get URL from them to connect again, if there is network drop.
(If we don't get the URL to re-connect, we have to start the process from beginning).
- Type your problem in notepad in detail, once you access to support, immediately copy & paste your problem in support.
Note:
1.You can allow them to connect your laptop remotely.
2. When 1st level support, transfers support to 2nd level, it might take sometimes more then 10 minutes
(It means 1st level support guy drops, we are put in query for second level support, till 2nd level technical guy picks up the support we have wait and there won't be anybody to answer during that waiting time )