I recommend that you do not copy MDF file as your backup in future. In most cases the database must be "stopped" in order to allow copying of MDF file, and at other times if you are able to make a copy it will be inconsistent / corrupted when you copy it back against.
If you have copied back your database from MDF file-copy I recommend that you check its consistency:
DBCC CHECKDB WITH NO_INFOMSGS, EXTENDED_LOGICAL_CHECKS, DATA_PURITY
In future I recommend that you use the BACKUP command to make a backup file - I recommend that you turn on COMPRESSION for backups - that file will be smaller than your MDF anyway, and much smaller with Compression, so will save I/O time and disk / tape space.
You might want to have a look at Minion Backup, that will perform backups of all your databases in a structured fashion.