Also the AT firmware that a module comes with by default, varies according to the source of the supply. I have had modules with v0.9, 1.5, 2.0 and even 3.0. So it is difficult to restore exactly to what it came with unless you noted the version at that point. There may be some differences between the versions but I have only used the basic commands which seemed to work on all versions.
To add further to the confusion espressif had 1.5 for a while on their official site, went to 2.0, but now seemed to have reverted to 1.5. The electrodragon site is a good source of information for binaries and flashing tools and has a copy of the v2.0 at http://www.electrodragon.com/w/File:V2. ... rmware(ESP).zip
When I want to revert I normally use that 2.0. I haven't found the bin for a 3.0 that some recent modules came with.
There are as you say various flashing tools that can be used. When I need to I normally use the official tool as described at http://www.electrodragon.com/w/Category ... Code_Guide. Note that you need the whole directory containing the exe not just the exe file.