Hello again Sam,
thanks for the reply. No worries at all for the delay. I've used BC before for problems and am amazed by the help you guys give out!
The help is my pleasure! ...And since you've been amazed before, I'm going to have to work hard to live up to your previous experiences at BC!!! (Hopefully I won't let you down!! )
I'm a bit unsure about how to go about reformatting. The laptop runs Windows 10, it didn't come with any recovery discs or such like, I've read about the 'reset PC' option in the security settings of windows 10. Is this the equivalent to a full format and what I should be looking to do?
Good question! ...And to fully answer your question it will take a bit of knowledge, on exactly how the hard drive in your computer works.
...And I'm not 100% sure of your current level of understanding about hard drives or computers, so let me try to briefly explain how this happens...(and please go easy on me...I've never actually explained this to anyone before in a "beginner-through-advanced" way! )!
When you delete a file on your computer, your computer doesn't actually delete and remove the file, it simply removes a "pointer" to that file. When the "pointer" to that file is removed, the part of the hard drive that "reads" and "writes" data, will see that particular space as "writable". And over time, the place where your "deleted file" (that actually still exists on the hard drive) can, and will be overwritten at some point.
Before the data gets overwritten it can, in many cases, be fully recovered. ...However once the data has been overwritten, that task becomes extremely difficult, and in some cases it becomes impossible...
This is exactly why some of those "File Recovery" tools out there, depending on your situation, actually work! It is possible to go in and replace (or reset) that pointer, so that your 'deleted files' can sometimes be recovered (as long as you don't wait too long on a machine that gets used very often).
Now, with that being said, let's get back to answering your question:
The "Reset PC" option is just as thorough as a reformat, as long as you use the "Remove Everything" function. ...But there is a bit more to it, than that. Once the 'Remove Everything' option is chosen, you are given another choice:
Just remove my files
Remove files and clean the drive
And sometimes there is a "Restore Factory Settings" option as well (that I won't cover unless you have that option and would like to use it).
Selecting "Just Remove My Files" will essentially reformat the disk, but only in a partial manner.
The files themselves will not get removed. Only the "pointers" to those files (as explained above) will get removed over a finite block of data on the disk. And whatever files or information actually left on the disc in that block, are susceptible to being overwritten. This effectively renders any malicious files that were on the disc harmless. And I'm not 100% sure, but I believe both will reset your firewall settings (and that's very important in your case if indeed a backdoor was opened during the TeamViewer session).
So, in your case the option to "Just Remove My Files" should do the trick. ...And to be honest, if it were my system in your case, I would test that option straight away!! That way, you'll always have the second option to fall back on in case your firewall settings didn't get reset on the first one!
But in any case, I would STILL save your personal pictures that you want to keep onto a thumbdrive or similar media...You could always use MBAM (Malwarebytes Antimalware) to scan a plugged-in thumbdrive (with your personal info on it) from any other computer that has MBAM installed.
I hope this helps in answering your question!
...And while writing this, I did a couple of searches to find you some web pages with instructions and screenshots. I hope these will also help you if you're still unsure about how to continue.
But be aware!!! I did not fully read over, or filter these links!!! --- I simply found some links for you to read so that you'll have a much better idea of what to expect, and you'll know what was coming! So don't take the links above as any golden rule.
So if you're still unsure or are worried about something in the links, don't hesitate to bring it to my attention!
Please let me know if you're feeling more confident now, or if there is anything else you'd like to discuss!