Garden lawn full of weeds!

[Rainbows41]

Please help.
My garden lawn is now full of weeds when previously it was fairly lush. No matter how many times I pull the weeds out, they come back multiplied.
Also, there is a type of weed growing all over the whole area - purplish in colour, which is killing the lawn. My lawn looks really bad and it's getting me down.
Is there any way of rectifying this?
I have included a picture of the lawn. You can still see some small patches of what the grass used to look like but most of it is covered in weeds.

You need to use a lawn spot weedkiller spray (on a still calm day with no wind at all) and spray each weed thoroughly. Don't cut them back first, you need maximum leaf coverage. Leave a week and then mow the lawn, and DO NOT put the lawn clippings in the compost or in garden waste, put them in the ordinary wheelie bin. That applies to anything that has been treated with weedkiller.

Mowing can still be done regularly at this time of year, until the daytime temperature starts to fall below 7 degrees which is when grass stops growing.

Continue to spot treat the weeds as they appear, all through winter, and hopefully by spring a lot of them will have gone.

That's great advice. Thank you.