Normally, the law provides u/s 249 that Appeal shall be filed within 30 days from the receipt of the order of the Assessing Officer. However , u/s 249(3) provides that CIT(A) may condone the delay if he founds that the appellant was prevented from filing appeal due to genuine reasons.
You can also get relief by filing an application u/s 264 before the jurisdictional Commissioner of Tax for quashing the order passed by the A.O. The time limit for filing appeal u/s 264 of the I T Act is ONE year from the date of receipt of the order. So you can , Still file , an appeal u/s 264 before the Commissioner of Income Tax .
Remember, if you file an appeal before CIT(A) , you can not file simultaneous application u/s 264 before the CIT. Only either of them can have your petition.