Life threatening diseases in both male and female are Brain tumor, stroke, hemorrhage and multiple sclerosis (MS). The most common and widespread disease among these brain diseases is Brain tumor.Early and accurate diagnosis of brain lesion is vital for determining accurate treatment and prognosis. However, the diagnosis is a very challenging task and can only be performed by specialists in neuroradiology.A dataset of 30678 patients are collected from Government Hospitals and Private Hospitals in West Bengal before COVID-19 and after COVID-19. The classification of patients is based on three classes- Normal, Sign of Tumor and Presence of Tumor. The reports of MRIs of patients in January 2020 and February 2020 are collected from different hospitals. It is treated as dataset before COVID-19. Reports of MRIs of patients in April 2020 and May 2020 are dataset during COVID-19. The table of June 2020 is only shown. The entire datasets are accumulated for testing of any change in patients MRIs after the official announcement of new virus COVID-19 in March 2020. The aim of the paper is in two parts. The first part proposed a method for detection of five major types brain tumours. The second part is to make a comparison of any change in size of tumour in MRIs of patients before and after COVId-19. All collected MRIs reports are diagnosed by radiologists of hospitals.