There is no universal password or backdoor password for Zip files. If you do not know the password, you should contact the person or company from whom you obtained the Zip file to request it.
In some cases, when you attempt to unzip files from (extract) or view files in a Zip file (.zip or .zipx) a Decrypt dialog will display requesting a password. This indicates that the files in your Zip file have been encrypted.
The password for an encrypted Zip file is set by the person who creates the Zip file at the time it is created. It is also possible to encrypt files in a Zip file after the Zip file is created, but the person choosing to encrypt is the one who sets the password.
If you created the Zip file and are certain that you did not encrypt the files, it is likely that this Zip file has become corrupted in some way. One unusual possibility would be that your computer has been infected by a variety of the Cryzip virus. For information regarding this virus, please refer to an antivirus company webpage such as the one from Symantec.
WinZip Computing does not have anything that can help with the recovery of lost Zip file passwords (.zip or .zipx). If weak,Zip 2.0 (Legacy)encryption was used, the best that can be suggested is that you search the internet for an application to help with the recovery of passwords. There have been such applications available in the past, but we have not and do not research such things. WinZip Computing does not offer support, advice, or recommendations regarding any available programs for password recovery.
If your Zip file was encrypted using AES encryption, we know of no reliable methods for recovering a lost password.
