How can I lock or encrypt a file or folder in Windows?
I suggest and use pgp 6.5.8 ckt version [ http://www.wisegeek.com/what-is-the-best-version-of-pgp.htm ]
it handles everything you'll need to do and is freeware
have a look at these articles:
Encrypt Sensitive Data with TrueCrypt
How to Hide Folders Using 7 Free Apps
2 Ways to Hide “Important” Files and Folders in Windows
How To Lock Windows Folders With MyLockbox
You should also consider a software program called Truecrypt. I have used it for years and it is virtually unbreakable.
I agree that encryption software is the way to go. Most of them lock any type of file or folder, as well as flash drives. The software I use is called SensiGuard. I like it better than TrueCrypt because it's much easier to use.
Just follow the directions below:
Click Start, point to All Programs, point to Accessories, and then click Windows Explorer.
Locate the file that you want, right-click the file, and then click Properties.
On the General tab, click Advanced.
Under Compress or Encrypt attributes, select the Encrypt contents to secure data check box, and then click OK.
Click OK. If the file is located in an unencrypted folder, you receive an Encryption Warning dialog box. Use one of the following steps:
If you want to encrypt only the file, click Encrypt the file only, and then click OK.
If you want to encrypt the file and the folder in which it is located, click Encrypt the file and the parent folder, and then click OK.