Hidden folders - can I delete them

Dear Forum,

I recently learnt that you can see the folders that stay on your computer and impair the speed that it uses to process - for say start up.

I recently cut and pasted these folders - some were folders - some were just .bmp or .gif's from My Pictures to my Hard drive which is external.

Is it alright to delete the following folders - I am not too sure on folders like thumbs - when you don't know - I have opted not to touch.

I think that is what is wrong with my Hard Drive as I think I changed the sharing properties and then all of sudden it did not work. Keeps asking me to format it. Never done it before.

I am not too sure as I have some great work that I have created on the hard drive - I am a bit upset at myself if I created the problem by downloading programs for my mobile that are required on another computer and created a mess.

Thank you

I have already moved them - does that matter - will be a lot to undo.

How do you do a restore point?

I will keep them deleted. I am not too sure what to delete and what not to delete.

Perhaps a good idea to back up - I have a general idea of how to. It is that the reference to a database when I was deleting alerted me and I got very worried.

My hard drive is currently playing up and very unstable.

How do you back up and create a restore point?