Thanks for reaching out. We are sorry for the trouble with Lightroom. We are here to help!
Could you please share the Lightroom version and the operating system you are working on, and if you are working on a mobile device(Android/iOS), please confirm the operating system version of that too? Do you notice any error when you try to export the photo out of Lightroom?
Please check these articles to help you get started with Adobe Lightroom (Desktop): https://helpx.adobe.com/in/lightroom-cc/tutorials.html
& Adobe Lightroom (Android/iOS): https://helpx.adobe.com/lightroom-cc/using/lightroom-mobile.html
Please let us know if this helps!