How to proceed when microsoft defender, and malwarebytes is not detecting a trojan horse virus/malware on my hp laptop?

The pop‑ups shown are typical of a tech‑support scam page, not proof that the device is actually infected. If Microsoft Defender and other reputable antimalware tools are not detecting anything, proceed as follows:

1. Close the scam page and browser
   • Use Ctrl+Alt+Del → Task Manager → end all browser processes (for example, Microsoft Edge, Chrome, etc.). This closes the fake warning page.
2. Update Microsoft Defender Antivirus
   • Select Start > Settings > Update & Security > Windows Security > Virus & threat protection.
   • Under Virus & threat protection updates, select Check for updates, then under Threat definitions, select Check for updates to ensure the latest definitions are installed.
3. Turn on cloud‑based protection and sample submission
   • In Virus & threat protection, select Manage settings under Virus & threat protection settings.
   • Make sure Cloud-delivered protection and Automatic sample submission are both On. These features significantly increase the chances of detecting new or rare malware.
4. Run a full Microsoft Defender scan
   • In Virus & threat protection, select Scan options and run a Full scan. Close other apps so the scan can complete more quickly.
5. Run Microsoft Defender Offline if threats keep reappearing
   • If the same threat keeps coming back or there is suspicion of hidden malware, in Scan options choose Windows Defender Offline scan and select Scan now. The PC will restart and scan outside of Windows to catch threats that hide during normal operation.
6. If nothing is detected but activity still looks suspicious
   • Collect any suspicious files (for example, a recently downloaded installer) and submit the files to Microsoft for analysis. This helps detect previously unseen trojans.
7. Avoid the source of the scam
   • Do not call any phone numbers or click any buttons shown in such pop‑ups. Avoid sites offering illegal or pirated downloads, and keep using a modern browser like Microsoft Edge, which uses Microsoft Defender SmartScreen to help block malicious sites.

If malware has caused serious or irreversible changes and normal cleanup does not help, consider backing up important files and using Windows recovery options to reset or reinstall Windows.

References:

• Troubleshoot problems with detecting and removing malware
• Antivirus and antimalware software: FAQ
• Trojans
• Windows defender scam - Microsoft Q&A