Is an employee entitled to claim from his manager the cost of a travel ticket he lost due to the manager's retraction of his initial approval for the probationary leave?

If the manager promised to buy a ticket and then reneged, he must compensate you for the damage you incurred. The majority of scholars hold that a promise is binding if it results in a cost to the promisee, and the Islamic Fiqh Council has affirmed this. However, if you were able to cancel the ticket and did not do so, then you are not entitled to claim compensation.