Well i think i may of accidentaly delted something, all my sound does now is beep that comes from the computer ! it says somthing about no audi contraller

Please can some one help me.
Thank you
my pc info
I have been trying to solve this for months and would really really appreciate the help !!!!
Windows XP Home Edition Service Pack 2 (build 2600) Dell Computer Corporation Dimension 2400
System Service Tag: FTM3T0J (support for this PC)
Chassis Serial Number: FTM3T0J
Enclosure Type: Space-saving
2.40 gigahertz Intel Pentium 4
8 kilobyte primary memory cache
512 kilobyte secondary memory cache Board: Dell Computer Corp. 0G1548 A00
Serial Number: ..CN7082135RD0NX.
Bus Clock: 533 megahertz
BIOS: Dell Computer Corporation A00 05/23/2003
79.99 Gigabytes Usable Hard Drive Capacity
54.73 Gigabytes Hard Drive Free Space
HL-DT-ST DVD-ROM GDR8162B [CD-ROM drive]
SAMSUNG CD-R/RW SW-248F [CD-ROM drive]
3.5" format removeable media [Floppy drive]
IC35L090AVV207-0 [Hard drive] (80.00 GB) -- drive 0, s/n VNVC02G3CZN02T, rev V23OA66A, SMART Status: Healthy
Multi Flash Reader USB Device [Hard drive] (1.01 GB) -- drive 1
510 Megabytes Installed Memory
Slot 'DIMM_1' has 512 MB
Slot 'DIMM_2' is Empty
Tyvm all i hope this is the info needed !