Yaru is a compact, portable Registry viewer with some very unusual features.
For example, one of the reasons the Registry is a dangerous place is that when you delete something, there's no "undo" (at least, not with Regedit); it's gone forever. Yaru, however, can scan for and list at least some deleted Registry keys.
We tried this, going to HKEY_LOCAL_MACHINE\SYSTEM\Software on a test PC and deleting a leftover key. And sure enough, on launching yaru and clicking File > Open System, all the deleted keys were visible. A right-click option exports these to a file, and this can be imported to Regedit to restore the missing data.
(Please note, any Registry data you delete may be overwritten very quickly, depending on its location, so yaru will never be able to offer any guarantees. Still, it's good to have a capability like this to hand, just in case you need it.)
Yaru also has a powerful search tool, which can for instance find keys created during a particular date range, or look for text strings in unallocated Registry space. The program can also compare snapshots of a particular Registry hive. And yaru offers a host of reports to provide detailed information on every aspect of your target system.
There's plenty of power here, then, but accessing it isn't always straightforward: yaru is aimed at expert users and there's very little help. Still, even if you only ever use something like its ability to view deleted Registry keys, that's probably enough to justify downloading the program, and we'd recommend you give it a try.
Yaru provides all kinds of powerful low-level Registry features in a single, 1.4 MB portable executable. The program makes few concessions to beginners, though, so if you're not an experienced Windows user then it may take some time to figure out how everything works