Is the inability to perform 'Umrah in the first ten days of Ramadan due to the magnitude of sins, and what can be done in one's home country to obtain a reward equal to that of 'Umrah?

Thank you for your eagerness to do good. We ask Allah to record for you the reward of 'Umrah (definition) for your sincere intention, for a servant may attain through his intention what he cannot attain through his actions. It is not necessarily the case that your inability to perform 'Umrah is due to the gravity of a sin. Repentance from sins is one of the most important obligations. You should strive to do many good deeds and be keen on performing an action that few do but has abundant reward, which is: "Whoever prays Fajr in congregation, then sits remembering Allah until the sun rises, then prays two rak'ahs, will have a reward like that of a complete Hajj and 'Umrah."