HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed,...................

Open PowerShell–>run as administrator
Run below script

cls
[system.reflection.assembly]::loadwithpartialname(“microsoft.sharepoint”)
$web = Get-SPWeb http://SP2010
$web.CustomMasterUrl = “/_catalogs/masterpage/v4.master”
$web.MasterUrl = “/_catalogs/masterpage/v4.master”
$web.Update()