You’ve accidentally deleted some irreplaceable images. There are no backups; file recovery tools can’t find anything; it seems like they’ve gone forever. But wait: there may still be just a little hope.

Browse a folder in thumbnail view and Explorer generates thumbnails for every supported file, saving them in a local cache. These can live on for a long time, even if the source files are deleted, corrupted or otherwise trashed. And you can recover any or all of them with just a couple of tiny free tools.

Thumbs Viewer is a portable program for viewing the basic thumbnail databases you’ll find in folders like Pictures (Thumbs.db, ehthumbs.db, ehthumbs_vista.db, Image.db, Video.db, TVThumb.db, and musicThumbs.db). Its 43KB download size should tell you there’s nothing sophisticated here, but grab, unzip and run it anyway.

Click File > Open and choose your database to see its contents (if you can’t find one, make sure Explorer is set up to view hidden files).

Click an entry in the cache and it’s displayed in a preview window

Initially this display looks, well, disappointing. A horribly cryptic filename (you won’t see the original, sadly), useless low-level details like “Sector index”, and – on our test PC, at least – a “Date Modified” column which was always completely blank.

Click an entry in the table, though, and a preview window opens to display it. Resize this, if necessary, to show the whole image. All you then really need to know is that the thumbnails are displayed in date order, and the most recent are at the bottom of the table. Click on one of these, scroll up or down with the cursor keys, and the preview window updates accordingly. Click File > Save Selected to save that thumbnail, or use File > Save All to save everything.

Windows Vista and later stores its thumbnails in more centralised caches, named thumbcache_*.db and iconcache_*.db. These use a different structure, but fortunately Thumbcache Viewer can open and display them. It’s from the same developer, and works in exactly the same way: open your database (Start by looking in \Users\<UserName>\AppData\Local\Microsoft\Windows), click an entry in the table, and save individual images or the whole lot.

There are some very obvious issues with this technique. It won’t find images in folders which Explorer hasn’t cached. Disk cleanup tools will sometimes delete the thumbnail cache (see “Thumbnail Cache” in CCleaner, “Thumbnails” in Windows’ own Disk Clean-up). And of course it can only ever retrieve a thumbnail of the image, not the original.

Still, the idea can help to give a better idea of what someone might be viewing on a PC. And while the 96 pixel wide thumbnails aren’t much use, we found plenty of 1024x images on our test PC, potentially an extremely valuable record of the source.

Thumbs Viewer and Thumbcache Viewer are available now. Give them a try, see what you can uncover.