Before 3 days Task manager is running good enough but certainly now  my Task manager not showing network usage from few days,i think an 3rd party software has corrupted its features to never reveal his network usage.
I talked with Microsoft Answer Desk about this, but nothing  helped,they told that Task manager is windows features that can't be Re-installed to solve this problem.
When i go to "Resource Manager" it shows which application is using net be can't tell how much.The problem is only occurring with Task Manager WHAT TO DO !!!!!  Visit this Screen Shot----                          http://i.gyazo.com/11ea8ab1e44e5ce87906cfe56d92473e.png

• Edited by Nitesh Esteem 21 hours 44 minutes ago

You could restore your pc the time when it was working.

http://windows.microsoft.com/en-us/windows-8/restore-refresh-reset-pc