If your UK study visa is lost, report the loss immediately to the nearest police station and obtain a police report. This document is essential for your visa reapplication or replacement process.
Next, contact UK Visas and Immigration (UKVI) to inform them of the situation. You will need to apply for a replacement visa by submitting Form TOC (Transfer of Conditions) along with the police report, a valid passport, and proof of enrollment. Processing times vary, so apply as soon as possible to avoid disruptions to your studies. Keep copies of all documents for future reference.