Still Need help with theme/store

This was my original question;
Hi, I need help with my site by mistake I changed the theme I was trying to do a woocommerce store. By mistake I changed my site I am sooo upset I don’t know what to do I would like it to go back to the original yellow color and the original theme I had it please,please help I worked so many many hours doing it.HELP!
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Today;
I found my original color(theme twenty sixteen) but now I don’t see
the menu or topics on the right side
or any thing on the side that should be there how do I get it back
and I still do not know how to put in the woocommerce store thanks.this morning i made a back up as to not lose my info.