Right guys i aint technical so ill try explain this best as i can...My volume oan my computer has disappeared ..Ive went into control panel > sound and devices > and my volume setting is right at the very bottom so it needs to be right at the top..But the thing is it wont let me drag the wee bar along to the top

In the past this has been the problem but its always let me drag it back up to the top but this time it wont let me click on it and pull it, Any ideas?

Cannae listen to music or watch films , Nippy as ****!!