Solution 1 (Use Filezilla):
Connect your FTP client to your web server and then locate the file you want to CHMOD.
In FileZilla, right-click the file on your web server and choose File Permissions to open the file attributes.
Your FTP client may use different terminology.
The Change File Attributes dialog box opens.
Type the correct number in the Numeric Value text field.
This is the number assigned to the permissions you want to give the file. Most often, you’re given directions by the plugin or theme developer on which permissions number to assign to the file or folder, and typically, it’s either 644 or 755. You see the permissions are assigned with 755.
The file saves with the new permissions assigned.