Many new Microsoft Windows computers come with “trial” versions of paid anti-virus services.  For example, your laptop may come with Mcafee or Norton trial versions pre-installed.  These often only work for 3 months, after which they stop working until you pay them a fee.

This means that after 3 months your device is unprotected.

Windows 8 and 10 come with a free anti-virus service built into the Operating System, called Microsoft Defender.

Microsoft Security Essentials can be manually installed, for free, on Windows 7 and Vista.

However, while the Norton, Mcafee or other anti-virus is installed, even if it is not working, Microsoft Defender is turned off.

You must choose to:

• pay the fee and have the existing anti-virus activated again,
• choose to buy a different anti-virus program or use a free one
• use Microsoft Defender for free.

Before you install Microsoft Defender, or another anti-virus program, you must first uninstall the existing one.  Here’s how:

http://www.computerhope.com/issues/ch001402.htm

Once this is done Windows Defender should start automatically.  If it does not, here is how:

http://www.pcadvisor.co.uk/how-to/windows/how-turn-on-defender-in-windows-10-3466684/

For further information on keeping your device secure:

http://www.computerhope.com/vlist.htm