The value of items are determined by their condition and if they have original parts, or not.
The desk is probably not worth much because it is not in good condition and is missing major parts. The roll top is missing, as is the divider insert that would typically be used for letters and desk related items.
One man's silver is another man's gold. Your desk is unique as it appears to have scroll brackets from the bottom of the desktop to the legs. Cool.
If you turn the desk upside down, you may find a maker's mark. Or, pull the drawer out and inspect all sides of the drawer for a label or marking. Desks like yours were typically made of maple wood or perhaps cherry.
Based upon the lock, I did some research and found the below link that you may be interested in. The Eagle Lock Co was in business from 1833 through 1975. So, IF the desk was made the last year the lock company was in business, you have a 44 year old desk, at least.