Removing site title also removes menu in Twenty-Ten theme

i suspect, that your html structure is somehow broken, so that the #site-title div is not closed before the menu.

link to your site?

does your site validate? https://validator.w3.org/

my site is https://www.getafreewebsitefast.com

I restored the #site-title tag so that the menu reappears. Should I take it out again?

First up, stop editing twentyten. Your changes will be lost
https://go.rvoodoo.com/WPchild

and then, peep this:
https://voodoopress.com/2011/02/removing-site-title-and-description-to-finish-off-our-header-in-twenty-ten-child-theme/

i have no problem to remove the site title with #site-title {display: none;} and leaving the menu intact. (firefox)

or you can add the display: none; to the existing code in style.css:

#site-title {
	float: left;
	font-size: 30px;
	line-height: 36px;
	margin: 0 0 18px 0;
	width: 700px;
display: none;
}

That worked. Thanks alchymyth!