[A350-900]

My laptop’s Kaspersky anti-virus subscription expired some time back and I omitted to renew it (although it can still perform a scan, which I don’t understand!).
Yesterday, when I opened my files on the laptop drive and also an external drive connected to the laptop, pop-ups repeatedly appeared notifying of ‘Interrupted actions’. When I tried to close these pop-up (about 3 or more of them, repeating the same message), the file/folder got automatically deleted/transferred to the Recycle Bin, or (in the case of the external drive file, the file/folder could not be opened.
When I located the deleted file/folder in the Recycle Bin and clicked on it, a pop-up appeared with message: “Are you sure you want to permanently delete this folder?”.
I understand i may be able try to resolve the situation by re-starting on “Safe Mode with Networking”, and from there, attempt to renew my expired Kaspersky antivirus, and then do a scan of the system. Is this the correct approach?
I attempted to do the above, but got stuck at the Safe Mode re-start process: At the prompt to insert my password (i believe this is referring to the PIN (and not the miscrosoft password) because my name already apprars above the password field), the system keeps telling me the password is incorrect (despite me double-checking repeatedly that it’s correct). Thinking it might instead be the Microsoft password it is asking for, but even this was rejected.
Please help. What should i do next?