Q.Weeds growing in my dead nettle
Very green and straight standing grass type (weed I guess) is invasive in my dead nettle this spring. How do I get rid of it without killing my dead nettle, if possible. I used one spray that said kills weeds but not flowers. However, it did nothing and the grass (weed) was just as green and the flowers burned.

The best way to get rid of a weed without harming surrounding plants is to pull it by hand - try to remove the whole plant with its roots. Gardening tools can also assist you with removing the weeds manually such as a hoe or a winged weeder.
If the above option does not appeal, then here is an article that outlines other methods of dealing with weeds in your garden:
https://www.gardeningknowhow.com/plant-problems/weeds/weed-control.htm