I installed wamp server 2.5 in my windows 7 64 bit laptop but during the process I got error of missing msvcr110.dll. So I googled and found out that some redistributable can be installed from microsoft and then wamp server functions properly. But to my surprise even after that it did not function properly showing the tray icon in yellow where I could not even click.
Take a look at this thread, they have discussed numerous ways to solve the issue.
If you are running WAMPServer 2.5 you also need the VC11 redist. Visual C++ Redistributable for Visual Studio 2012
29.08.2014 with WAMP 2.5 I agree that VC11 is needed and it is not a bad idea to have previous distributions installed. It will be needed by other application. I am not sure if you need bit 32 version
http://www.microsoft.com/en-us/download/confirmation.aspx?id=30679