>>delete your cookies and carry on browsing!
This is nothing to do with cookies.
Often these types of ransomware put some graphics image up on the screen and wont let you in no matter what you do (you are effectively locked out your computer).
You can boot up the computer in safe mode and then run some sort of security software.
Or you can download the Kaspersky Rescue Disk for free (on another computer obvisouly), "make" a CD of it, then "boot" your computer using this disk and run the security software on that disk.
This will probably get rid of your ransomware.
p.s. It is always worth have a "spare" Windows logon that you dont use which can be used if you get logged out of your computer on your normal logon.
Then you can run you security software from this "spare" Windows logon and hapefully get rid of the malware.