Bishwas-py Are you using a public directory for your installation ? Looking at the .htaccess file you posted, it seems that this is not correct
RewriteRule ^vendor/(.*)?$ / [F,L]
RewriteRule ^storage/(.*)?$ / [F,L]
RewriteRule ^config.php$ / [F,L]
# RewriteRule ^api(.*)$ api.php [QSA,L]
# RewriteRule ^admin(.*)$ admin.php [QSA,L]
If you are nor using public then you should remove the # from the lines above. If you are using public then you should comment those lines out
