Thank you for reaching out and using Adobe XD . Can you please try signing In Adobe XD back with the same Id which you used before formatting the computer.You will able to retrive your document in the "Cloud Documents" tab,you can see cloud docs even If you use the free version of XD with limitation.Also you can go to assets.adobe.com. Here you will find all your files, as long as they have been saved to the cloud. Also as you have mentioned you have formatted the computer ,not deleted files from cloud docs then all your saved cloud files will be present in cloud docs as long as they have been saved to cloud .Hope this helps.
please feel free to update this discussion in case you need further assistance and we will be happy to help.