how to check whether things have been deleted or not?

CCleaner for Windows
1

eg where do I find temp files and thumbnail cahe to check they have been deleted ?

2
. . . where do I find temp files and thumbnail cahe to check they have been deleted ? . . .

My current thumbnail cache is stored in C:\ Windows\ winsxs

Type temp into your search engine and you'll find scads of hiding places.

3

If you used the secure delete option, and wish to verify that it did indeed get rid of files you can verify using Recuva.

4

where do I find temp files

Type %temp% into the Windows Explorer address bar.