I was making adjustments on the layout under my theme.css file. However the power went out suddenly and I didn’t have the time to save. When I back to the site it appears the layout is messed up. Would someone be able to tell me how can I troubleshoot where the issue is please?
Unfortunately theme assets, non liquid non template files, do not have version rollback.
And this issue is present on your live site?
Have you heavily customized your CSS previously?
If not and If your using a shopify theme store theme simply download a new copy and copy the theme.css file over, again make backups before you do potentially destructive action.
Did you make a backup?
Do you have a link to a preview that is not damaged? > view source (ctrl+u) and find your css file url though unfortunately due to shortsighted stupid reasons it will be minified.
But if you’ve invested a lot of work it could be used to mesh together with fresh copy by an expert.
If none of those resolve the problem you heavily modified your theme.css with not backups will need to contact shopify support and hope they can help