What accidental key press's would delete large amount of typed email?

This is for someone else who was infuriated this morning when a large portion, about half, of a large email just randomly disappeared. She thinks it happened right as she hit "SHIFT+ a number" and could have possibly accidentally hit control instead of shift. She doesnt know the number though. It deleted mid word about half way through a paragraph, which was about half way through a 1.5 page email. She certainly didnt highlight the area and then use the shortcut for "cut" and all the shortcuts Ive seen through googling must have the portion highlighted for it to delete it. The odd part is that it was cut off at the exact same spot in the draft folder as well which is way too much of a coincidence for it not to have also altered the draft. Email client is gmail, all settings default, OS is win 10 home premium with all default settings.

She mentioned that it happens a few times a week, starting when she upgraded from 7 to 10. Her laptop mousepad is not activated. She types pretty fast and thinks that she must have hit the wrong key combo but im at enough of a loss to resort to leaving a post here in hopes someone might know what she did so we can prevent it. I would like to solve this for he so hook me up friends.

CTRL-A would select everything, then the next keystroke would replace it all with that single character.

NavyLCDR said:

CTRL-A would select everything, then the next keystroke would replace it all with that single character.

Thanks for your response, I thought that too at first but what doesnt work with that combo is only half of the email was deleted. It cut it off mid word as well, so the select all types of cmds didnt fit, which is why Im stumped on this one, ty though for taking the time to try and suggest something for us. The email was about 6 paragraphs and all of a sudden the second half dissappeared cutting off mid word, mid sentence about half way through the text. An additional bit of info is the word at the cut off point had a capitol "A" connected, looked like "exampA" as an example and the blinking cursor was directly after the "A". And that is how the draft was as well, it's as if it deleted the gmail draft up to that point and added the "A" to the cut off word.

Not sure what might have deleted it but does she know Ctl-Z to attempt to restore from last action?