I am looking for a free program that can encrypt files on my hard drive and also when it is encrypted people must not be able to access the file or delete the file
I also use Truecrypt and it works well. You create a volume of size X that is one file on your HDD and then you store your files in the one file. Someone can however delete the file and then all the files in it. You should protect the volume with file and directory permissions then you will be ok.
Well I use TrueCrypt for some things, for other things there's BitLocker Drive Encryption, which is built into Windows Vista+ and you can just create a new partition and encrypt it.