How to update my Tomtom G50

https://uk.support.tomtom.com/app/products/detail/p/4243

How to update your TomTom device?

1. Make sure MyDrive Connect is installed on your computer. Download for Windows® ...
2. Connect your sat nav to your PC via the USB cable. MyDrive Connect will start automatically. ...
3. A new screen will open, login and choose the updates you would like to perform.

https://www.tomtom.com/en_gb/mydrive-connect/

To update the maps on your TomTom 610, use the MyDrive Connect software (from tomtom). If this tomtom software is not yet installed on your computer/laptop, download it from the tomtom website (e.g. www.tomtom.com) and install it. Then follow the instructions to update your map, after connecting your GPS device to your computer.
You may have to create a TomTom account (and register your device), sign in to your account, locate the replacement map or any new maps (of other regions) you wish to install, download the maps and install the map.
If you have a "lifetime" map (privilege) for your device, you won't have to pay (subscribe) for the updated map.

I'm assuming you have
- the TomTom HOME (or MyDrive Connect) software installed on your computer/laptop.
- you have a TomTom account and have registered your TomTom device (in that account) on the TomTom webiste
- you are able to successfully plug your TomTom device to your computer/laptop, e.g. using the USB (cable or cradle)
- you can log into your TomTom account and have the TomTom software (HOME or MyDrive Connect) recognize your device (as being connected)
- you see the list of software/data/map updates available for your device
... and you still can't download the software/data/maps ... ? to update your TomTom device ... ?

Have you been able to get any help/support from the TomTom website ? www.tomtom.com to do this ?

First, find the USB cable needed to connect your Tomtom unit to your computer. Go to the Tomtom update page (link provided below), download and install the software on your computer, and follow the update instructions on that page (about halfway down the page).
MyDrive Connect Update your GPS

you need to install software on your computer .
called mydrive connect
https://www.tomtom.com/en_au/mydrive-connect/
http://au.support.tomtom.com/app/answers/detail/a_id/13855/locale/en_AU
tom tom via is listed as supported by mydrive connect

Then buy the maps from tom tom .
However it should have some sort of map in it already ?

Make sure that you are using the latest version of MyDrive Connect.

Connect your navigation device to your computer and switch on your device.

MyDrive Connect starts and automatically checks if a newer version of your map is available. If you are entitled to the Latest Map Guarantee, MyDrive Connect offers you the latest map.

Click Continue and follow the on-screen instructions to download and install the available map.

Once the installation is complete, the installation screen will close and you are re-directed to the My Content page. Also, the status in MyDrive Connect changes to Connected.

When you see the MyDrive Connect icon on your computer and the message on your navigation device that the installation has completed, disconnect your navigation device from your computer.

your device has been updated

Visit the site www.tomtom.com/getstarted to discover which software (TomTom Home, or MyDrive Connect) is compatible with your device. After you download the appropriate software, run it to update maps (if available to your device) and install some goodies.

Find out which TomTom software works with your device (TomTom Home or MyDrive Connect), download it and install it on the computer. Connect the device to the computer. It should be recognized by the TomTom software. For TomTom Home, find the Update my TomTom and follow instructions. For MyDriveConnect create an account with TomTom and associate the device with the account. Once logged you will see what you are entitled to. If you do not see MapUpdate you are not entitled to free updates and you will have to buy the new maps.

There's a possibility that the navigation software is corrupted.
Have you tried to recover it from your backup (on your computer) ?
Otherwise, you'll want to use TomTom Home (or MyDrive Connect) to see if you can download and re-install the software from the tomtom webiste.
Recently, TomTom has decided to limit/stop support (including software/maps, etc.) for certain (older) models of TomTom GPS. If your model is one of those, you're out of luck. TomTom is trying to have you buy a new model.

Download the newest TomTom Home and install, then connect your TomTom to your PC. TomTom Home will detect your TomTom and do the rest.