replacement products r not generally new ones. Those r repaired one with same used time w.r.t to ur rma date. There r many free tools available which can recover and repair damaged partitions. Do a search in the forum here , go through them and u will get many solution.
If ur datas r important then,
1 First try to recover ur partition
2. extract all ur datas
3. use tool from ur hard disk manufacture site to search for disk error (dont try this until u recover ur data as to much activity of hard disk may further damage it if there is some mechanical error present as ur hd is of replacement type, possible).
4. do a fresh format.