Malware causes all kinds of PC problems, and they don’t always go away once the threat has been removed. You might still find you can’t run certain programs, web browsers don’t work properly, there are network issues, and more.

You can’t simply turn to System Restore or your last backup, either: restoring old files might reinfect your PC, and make your problems even worse.

Some of these issues can be addressed manually, although this isn’t always easy. Especially if, say, the malware has left REGEDIT disabled.

Fortunately there are plenty of free tools which can help, and in many cases they’re able to repair your PC in a couple of clicks.

File Extension Fixer’s repair options are all accessible from one screen

File Extension Fixer is a tiny portable program which addresses some of the most common post-malware problems.

If you can’t run a particular executable file type (EXE, MSI, BAT, CMD, COM, VBS and REG are supported) then the program can repair your file associations accordingly.

Malware may also try to prevent you running key system tools. File Extension Fixer can fix this in some cases, and has links to enable and run REGEDIT, Task Manager, System Restore and MSCONFIG.

Ideally you should run the program after removing any malware, but if this isn’t possible then File Extension Fixer can download and run Malwarebytes Anti-Malware and/ or Ultra Virus Killer.

None of this is too surprising, but it works well, is portable, and extremely easy to use.

Ultra Virus Killer is a powerful collection of tools which focuses on manual malware hunting, but also includes a System Repair module to help fix any damage.

The UVK interface is simple enough: there’s a list of fixes, you select the ones you need, click Run, and the program runs them all.

You get plenty of options, too. The program can reset your browsers (Chrome, IE, Firefox), restore the default HOSTS file and DNS settings, or reset your Registry and file permissions. It’s able to install and update various essential components (DirectX, Java, Flash, .NET), unhide files/ folders/ drives, fix executable file associations, clean up your system, register system DLLs, run SFC (the system file checker) and more.

There’s some advanced low-level Windows tweakery going on here, and if you’re not sure what a particular fix does then we’re recommend you leave it alone. But otherwise Ultra Virus Killer offers a lot of functionality in a convenient portable form, and it deserves a place in every geek’s troubleshooting toolkit.

Windows Repair (All In One) is a general purpose Windows problem-solver, but also includes many relevant post-malware fixes.

Windows Repair is packed with fixes, but be careful – applying the wrong one could cause more problems than it solves

The “Remove Policies Set By Infections” fix restores access to Task Manager, REGEDIT, the desktop, and generally gets your system working as it did.

“Repair File Associations” allows executable files to run normally again, and applies many other fixes. The program is very up-front about what it’s doing, too – all the changes are stored in REG files which you can browse and edit as you like.

There are some very detailed network repair fixes. “Repair Winsock & DNS Cache” clears the stored DNS cache and resets TCP/IP, for example, and the program shows you exactly which commands it’s using to do the job.

A wide assortment of more general low-level fixes are also on hand, such as restoring key Windows Services and setting them to their default startup values.

Whichever tool you’re using, treat it with caution. Setting key Windows components to their default configuration may sound like a good idea, but it could break some existing applications, perhaps forcing you to install them again. Only apply a fix if you’re confident it’s required.

That aside, if your PC is largely broken, you’re thinking of reinstalling Windows, and your documents and data are fully backed up, then these repair tools – even the relatively simple File Extension Fixer – are definitely worth a try. Download copies right now, store them safely somewhere, and you’ll be ready if disaster strikes.