AWS Storage Gateway and File Share disappeared from web console overnight.

It sounds like you might have the wrong region selected in the management console. You can find the region selection in the upper right-hand corner of the console screen. You can only see each gateway when the region where it resides in is selected.

A gateway that was launched successfully can only disappear entirely from the account and region in which you created it by calling the DeleteGateway API of the AWS Storage Gateway service. I suggest you scan your CloudTrail logs to see if that API has been called recently. The logs in this view cover the past 90 days in the account and region.

In the management console, open the CloudTrail console. Make sure that you're in the same region where you created the gateway that disappeared. Open the "Event history" view in the console, and in the "lookup attributes" dropdown, choose "Event name" as the field to filter by. In the text box, enter "DeleteGateway" as the event to search for.

If any events show in the search results, you can click them open to see details on the API call. You'll see when it was called, if your credentials or some others were used, which IP address the call was made from, and in the userAgent field, you'll usually also see if the call was made with a web browser (via the console) or with the AWS command-line interface (CLI) or some other tool. Note that unlike most of the other fields, userAgent isn't fully reliable, because a bad actor or criminal could put any value they like in it, but if you called the API yourself, it's generally a useful indication of which client tool was used.

If no DeleteGateway events are shown in the CloudTrail event history, check if you can find CreateSMBFileShare or CreateNFSFileShare events, depending on whether you were creating Windows-compatible SMB file shares or NFS file shares more typically used on Linux. If those events also aren't shown, it's very likely that you deployed the gateway in a different region or account.

You can find all the Storage Gateways across all regions in your account by opening CloudShell in the console in your preferred/primary region and copying this set of statements and hitting Enter. It'll loop through all the regions that are enabled in your account and looks for storage gateways of any type in each one. If there are no gateways in the region, it'll output an empty "Gateways" array:

for region in $(aws ec2 describe-regions --query 'Regions[].RegionName' --output text)
do
	echo "** ${region}"
	aws storagegateway list-gateways --region ${region}
done