PowerShell not working on Windows 2008 R2 -

i have accidently installed .net 4.5 on windows server 2008 r2 powershell 5.1, have reverted .net 4.0 version , powershell not working. gives below error.

windows powershell terminated following error: method not found: 'system.threading.tasks.task system.threading.tasks.task.run(system.action)'

what should resolve this?

you need download windows management framework 3.0 or install microsoft .net framework 4.5 correct issue.

windows management framework 3.0 - link

microsoft .net framework 4.0 - link

or can

windows management framework 4.0 - link

microsoft .net framework 4.5 - link

wiki