Don't do it like that!
Do not concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.
Surprisingly, that'll also cure your problem...
When you concatenate an array of bytes into a string:
byte[] data = ...
string s = "Byte Data: " + data;
It calls an implicit ToString on the array - which returns the type of the variable rather than the content as a string of some description.
So use parameterised queries (at all times) and it will pass the content directly:
SqlCommand comserv = new SqlCommand(" insert into FileInformation (FileName,FileType,FileData) values(@FN, @FT, @FD)", record);
comserv.Parameters.AddWithValue("@FN", FileName);
comserv.Parameters.AddWithValue("@FT", FileType);
comserv.Parameters.AddWithValue("@FD", FileData);
comserv.ExecuteNonQuery();